U.S. patent application number 12/103931 was filed with the patent office on 2008-10-23 for organic electroluminescence device.
This patent application is currently assigned to Idemitsu Kosan Co., Ltd.. Invention is credited to Kenichi FUKUOKA, Hisayuki Kawamura.
Application Number | 20080258613 12/103931 |
Document ID | / |
Family ID | 39871519 |
Filed Date | 2008-10-23 |
United States Patent
Application |
20080258613 |
Kind Code |
A1 |
FUKUOKA; Kenichi ; et
al. |
October 23, 2008 |
ORGANIC ELECTROLUMINESCENCE DEVICE
Abstract
An electroluminescence device including an anode, a cathode, and
an emitting layer interposed between the anode and the cathode, in
which the emitting layer contains a host, a first dopant, and a
second dopant, a luminous intensity of the first dopant is twelve
times as great as a luminous intensity of the second dopant or
greater, a content of the second dopant is 0.001% by mass to 0.5%
by mass, and the emitting layer is formed by a coating process.
Inventors: |
FUKUOKA; Kenichi;
(Sodegaura-shi, JP) ; Kawamura; Hisayuki;
(Sodegaura-shi, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
Idemitsu Kosan Co., Ltd.
Chiyoda-ku
JP
|
Family ID: |
39871519 |
Appl. No.: |
12/103931 |
Filed: |
April 16, 2008 |
Current U.S.
Class: |
313/504 ;
428/690 |
Current CPC
Class: |
H01L 51/0043 20130101;
H01L 51/0081 20130101; H01L 51/006 20130101; H01L 51/0039 20130101;
H01L 51/0059 20130101; H01L 51/0058 20130101; H01L 51/0071
20130101; H01L 51/5012 20130101; H01L 51/0056 20130101 |
Class at
Publication: |
313/504 ;
428/690 |
International
Class: |
H01J 1/63 20060101
H01J001/63; B32B 9/04 20060101 B32B009/04; C09K 11/00 20060101
C09K011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 20, 2007 |
JP |
2007-112154 |
Claims
1. An organic electroluminescence device, comprising: an anode; a
cathode; and an emitting layer interposed between the anode and the
cathode, wherein the emitting layer contains a host, a first
dopant, and a second dopant, a luminous intensity of the first
dopant is twelve times as great as a luminous intensity of the
second dopant or greater, and the emitting layer is formed by a
coating process.
2. The organic electroluminescence device according to claim 1,
wherein a content of the second dopant is 0.001% by mass to 0.5% by
mass.
3. The organic electroluminescence device according to claim 1,
wherein an energy gap of the first dopant is greater than an energy
gap of the second dopant.
4. The organic electroluminescence device according to claim 1,
further comprising an electron transporting layer interposed
between the emitting layer and the cathode, wherein an affinity
level of the second dopant is greater than an affinity level of the
host by 0.2 eV or more, and electron mobility of the electron
transporting layer is 10.sup.-4 cm.sup.2/Vs or greater at an
electric intensity of 0.25 mV/cm.
5. The organic electroluminescence device according to claim 4,
wherein the electron transporting layer contains a
nitrogen-containing heterocyclic derivative represented by a
following formula (1), HAr-L-Ar.sup.1--Ar.sup.2 (1) where HAr is a
substituted or unsubstituted nitrogen-containing heterocyclic group
having 3 to 40 carbons; L is a single bond, a substituted or
unsubstituted arylene group having 6 to 60 carbons, a substituted
or unsubstituted heteroarylene group having 3 to 60 carbons, or a
substituted or unsubstituted fluorenylene group; Ar.sup.1 is a
substituted or unsubstituted divalent aromatic hydrocarbon group
having 6 to 60 carbons; and Ar.sup.2 is a substituted or
unsubstituted aryl group having 6 to 60 carbons or a substituted or
unsubstituted heteroaryl group having 3 to 60 carbons.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an organic
electroluminescence device, and in particular, to an organic
electroluminescence device that has a long light-emitting
lifetime.
[0003] 2. Description of Related Art
[0004] Conventionally, an organic electroluminescence device
(hereafter abbreviated to OELD) described below is known.
[0005] An OELD includes an anode, a cathode, and an emitting layer
made of organic compounds interposed between the anode and the
cathode.
[0006] When voltage is applied to the OELD, a current flows through
the emitting layer.
[0007] Released energy from recombination of an electron and a hole
in the emitting layer is then taken out as light.
[0008] Here, a configuration in which the emitting layer is not
constituted by a single organic compound, but a dopant material is
added to a host material is known (e.g., Document 1:
JP-A-07-288184).
[0009] A dopant is normally doped to a host approximately in 0.1 to
20% by mass.
[0010] Such a configuration can provide an OELD with an excellent
luminous efficiency and an extended lifetime.
[0011] For further improvements, especially for extending a
lifetime, a dopant is known to be doped to the subsidiary layer
adjacent to the emitting layer instead of the emitting layer (e.g.,
Document 2: JP-A-2003-051388, Document 3: U.S. Pat. No. 5,989,737,
and Document 4: JP-A-2004-221045).
[0012] According to Document 2, a subsidiary layer (secondary
layer) adjacent to an emitting layer is provided to a hole
transporting layer or an electron transporting layer adjacent to
the emitting layer, and a color-neutral dopant that does not
contribute to luminescence is doped to the secondary layer.
[0013] According to Document 3, a polycyclic compound with a
condensed ring (specifically, rubrene) is doped to a hole injecting
layer.
[0014] According to Document 4, a red emitting layer is disposed at
a cathode side of a blue emitting layer, the blue emitting layer
being on an anode side and primarily emitting light.
[0015] Effects of these arrangements are disclosed to be driving
stability and an extended lifetime of an OELD.
[0016] According to the configurations disclosed in the above
Documents, however, it is inevitable that manufacture steps be
complicated in order to provide an extra layer other than an
emitting layer and a charge transporting layer.
[0017] Now, a single emitting layer contains a plurality of dopants
according to Document 5 (JP-A-2002-038140).
[0018] Listed as a plurality of dopants are three of the kind,
namely (i) an exciton trap dopant, (ii) a hole trap dopant, and
(iii) a luminescence dopant.
[0019] In an example disclosed therein, tris(8-quinolinol)aluminum
(Alq) complex constitutes a host, to which (i) 5% of rubrene is
doped as an exciton trap dopant, (ii) 5% of
4,4'-bis(N-(1-naphthyl)-N-phenylamino)biphenyl (abbreviated to NPD)
is doped as a hole trap dopant, and (iii) 2% of DCJTB is doped as a
luminescence dopant. It is disclosed that serviceable life is
extended as an effect of the arrangement.
[0020] However, in the OELD disclosed in Document 5, the amount of
the exciton trap dopants and the hole trap dopants are so large
that that the exciton trap dopants and the hole trap dopants
themselves emit light as a matter of course.
[0021] It results in deterioration of color purity of the color
emission of the luminescence dopant.
[0022] Moreover, it is very difficult to form a film of an emitting
layer from a host material and three dopant materials, which add up
to a total of four materials.
[0023] In addition, if film forming is conducted by
vapor-deposition as disclosed in the example in Document 5, it is
difficult for the four materials vaporized to be simultaneously
vapor-deposited entirely at a uniform concentration. Further,
film-forming by vapor deposition is not practical, since partial
unevenness in the concentration and therefore unevenness in
luminescence cannot be avoided.
SUMMARY OF THE INVENTION
[0024] An object of the present invention is to provide an organic
electroluminescence device that maintains color purity, allows
practical manufacture steps, and possesses a long lifetime.
[0025] An organic electroluminescence device according to an aspect
of the present invention includes: an anode; a cathode; and an
emitting layer interposed between the anode and the cathode, in
which the emitting layer contains a host, a first dopant, and a
second dopant, a luminous intensity of the first dopant is twelve
times as great as a luminous intensity of the second dopant or
greater, and the emitting layer is formed by a coating process.
[0026] With this arrangement, the second dopant is doped to the
emitting layer in addition to the first dopant that primarily emits
light.
[0027] The luminous intensity of the second dopant is very low
compared to that of the first dopant for primarily emitting light.
Therefore, the luminescence of the second dopant does not
deteriorate color purity of emission of the organic
electroluminescence device as a whole, so that color purity of
emission of the organic electroluminescence device is
maintained.
[0028] Although the second dopant does not contribute to color
emission, a small amount of the second dopant contributes to an
extended life of the organic electroluminescence device.
[0029] It should be noted that the luminous intensity of the dopant
refers to luminescence components from the dopant in the
electroluminescence luminescence spectrum obtained when electricity
runs through.
[0030] In general, a content of the first dopant contained in the
emitting layer needs to be more than that of the second dopant in
the emitting layer in order to determine the luminous intensity of
the first dopant to be higher than that of the second dopant. Also,
when a luminous peak wavelength of the first dopant is shorter than
that of the second dopant, the second dopant, rather than the first
dopant, is likely to emit light on account of transfer of luminous
energy of the first dopant to the second dopant or on account of
absorption and reemission of light.
[0031] By appropriately decreasing a content of the second dopant,
for example, the ratio of the luminous intensity of the first
dopant to that of the second dopant can be put twelve times or
larger.
[0032] In the above arrangement, the emitting layer is formed by a
coating process.
[0033] More specifically, a host material, a first dopant material,
and a second dopant material, each in a predetermined amount, are
dissolved in a solvent to provide an
organic-electroluminescent-material-containing solution. The
organic-electroluminescent-material-containing solution is dropped
onto a substrate, a base layer or the like, where the solvent is
evaporated to leave an emitting layer formed.
[0034] With this process, an emitting layer in which the first
dopant and a small amount of the second dopant are evenly dispersed
can be easily formed.
[0035] Conventionally, since vapor deposition has been employed for
forming an emitting layer, it was difficult for a plurality of
dopants with different concentrations to be simultaneously and
evenly deposited into a single layer.
[0036] Here, if a concentration of each of the plurality of the
dopants is increased (e.g., 1% by mass or more), the layer can be
evenly formed by vapor deposition, but in this case, the luminous
intensity of the second dopant is also increased to deteriorate
color purity of light emission of the organic electroluminescence
device as a whole. In other words, with vapor deposition, which has
been a conventional forming process, it has been impossible to put
the ratio of the luminous intensities of the first dopant and the
second dopant doped in an emitting layer at twelve times or
larger.
[0037] Thus, a secondary layer that contains a small amount of the
second dopant has conventionally been provided in addition to the
emitting layer that contains the first dopant. In this case,
however, the increased number of layers in an organic
electroluminescence device not only complicates manufacture steps
but also decreases the light acquisition efficiency.
[0038] In other words, it has been difficult to utilize a plurality
of dopants without increasing layers and deteriorating color
purity.
[0039] According to the aspect of the invention, since a coating
process is employed in the film-forming steps, the mixing ratio of
materials can be accurately controlled, and in addition, a material
mixed in a small amount can be evenly dispersed in the film.
[0040] Thus, the luminous intensity of the second dopant can be
limited to a value that does not affect the color emission of the
first dopant.
[0041] Therefore, according to the aspect of the present invention,
a plurality of dopants can be utilized to extend a lifetime of an
organic electroluminescence device, without deteriorating color
purity or increasing layers.
[0042] In the aspect of the present invention, it is preferable
that a content of the second dopant be 0.001% by mass to 0.5% by
mass.
[0043] Such reduction of a content of the second dopant enables to
reduce the luminous intensity of the second dopant to put the ratio
of the luminous intensities of the first dopant and the second
dopant at twelve times or larger.
[0044] In the aspect of the present invention, it is preferable
that an energy gap of the first dopant be greater than an energy
gap of the second dopant.
[0045] For example, an energy gap of the first dopant may be 2.9 eV
or more, and an energy gap of the second dopant may be below 2.9
eV.
[0046] With this arrangement, the emitting layer contains a small
amount of the second dopant that has a small energy gap.
[0047] Here, the second dopant serves as an electric charge trap
that traps electric charge (i.e. electron or hole) excessively
injected to the emitting layer to adjust electric charge
balance.
[0048] As a result, an organic electroluminescence device can
obtain an improved luminous property as well as an extended
lifetime.
[0049] Conventionally, poor injection balance of electric charge
has caused either of electrons and holes to be excessively injected
to the emitting layer, resulting in a lowered luminous efficiency
and a shortened lifetime.
[0050] Assumedly, this is because when the injection balance of
electric charge is improper, an emitting region is misaligned
toward an anode side or a cathode side of the emitting layer, or
the electric charge even passes through the emitting layer.
[0051] When the emitting region is misaligned owing to unbalanced
electric charge, sufficient performance of the luminescent material
is not sufficiently exhibited.
[0052] Moreover, if the electric charge passes through not only the
emitting layer but also the hole transporting layer or the electron
transporting layer, the electric charge recombines in the hole
transporting zone or the electron transporting zone, which causes
an extreme deterioration of the material, thus shortening the
lifetime thereof.
[0053] Here, according to the aspect of the present invention,
balance of the electric charge in the emitting layer can be
adjusted by the second dopant. Accordingly, the recombination
region can be controlled to be disposed at the optimum region to
maintain the luminous efficiency and to extend life as well.
[0054] In this case, since the content of the second dopant is
small, the color emission of the organic electroluminescence device
as a whole is not affected, so that the color purity can be
maintained.
[0055] In order not to have the emission of the second dopant
influence the color emission of the first dopant, it is preferable
that the content of the second dopant be small. On the other hand,
in order to have the second dopant properly function as the
electric charge trap, the materials have to be properly
concentrated.
[0056] For this reason, the content of the second dopant may
preferably be 0.001% to 0.5% by mass, may further preferably be
0.005% to 0.4% by mass, and may still further preferably be 0.001%
to 0.1% by mass.
[0057] Here, an energy gap refers to a difference between
conductive level and covalent electron level, which can, for
example, be defined by a value measured from an absorption end of
an absorption spectrum in benzene. Specifically, the absorption
spectrum is measured with a commercially available
ultraviolet-visible spectrophotometer, and the energy gap is
calculated from a wavelength at which the absorption spectrum
appears.
[0058] It should be noted that an energy gap need not be based on
the above definition, but may be any value capable of being defined
as an energy gap without diverting from the inventive concept of
the present invention.
[0059] In the aspect of the present invention, it is preferable
that the electroluminescence device further includes an electron
transporting layer interposed between the emitting layer and the
cathode, in which an affinity level of the second dopant is greater
than an affinity level of the host by 0.2 eV or more, and electron
mobility of the electron transporting layer is 10.sup.-4
cm.sup.2/Vs or greater at an electric intensity of 0.25 mV/cm.
[0060] With this arrangement, the drive voltage of the organic
electroluminescence device can be lowered by using an electron
transporting layer having high electron mobility.
[0061] Also, exciton energy by electrons and holes injected to the
emitting layer is transferred to the first dopant from the host and
acquired as light emission.
[0062] Here, if an electron transporting layer having an excellent
electron transporting performance is employed, the drive voltage
can be reduced. However, at the same time, electrons may be
injected to the emitting layer in excess.
[0063] Once the excessively injected electrons reach a hole
transporting layer (or an anode), the hole transporting layer (or
the anode) is deteriorated, thereby shortening the lifetime of the
organic electroluminescence device.
[0064] With regard to the problem, the present invention includes a
second dopant having an affinity level higher than that of a host.
In this way, the second dopant functions as an electron trap. The
second dopant traps the excessively injected electrons to adjust
the electron charge balance.
[0065] As a result, while the voltage is lowered by an electron
transport material having high electron mobility, the lifetime can
also be extended.
[0066] Here, an affinity level Af (i.e. electron affinity) refers
to ejected or absorbed energy when an electron is given to a
molecule of a material, which is defined to be positive in the case
of ejection and negative in the case of absorption.
[0067] The affinity level Af is defined by an ionization potential
Ip and an optical energy gap Eg as follows.
Af=Ip-Eg
[0068] Here, the ionization potential Ip refers to energy necessary
for a compound of each material to remove electrons to ionize, for
which a value measured with an ultraviolet ray photoelectron
spectrometer (AC-3 manufactured by Riken Keiki Co., Ltd.).
[0069] It should be noted that an affinity level need not be based
on the above definition, but may be any value capable of being
defined as an affinity level without diverting from the inventive
concept of the present invention.
[0070] Also, electron mobility can, for example, be measured by a
TOF (Time-Of-Flight) method, but may be measured by other
methods.
[0071] In the aspect of the present invention, it is preferable
that the electron transporting layer contain a nitrogen-containing
heterocyclic derivative represented by a following formula (1),
HAr-L-Ar.sup.1--Ar.sup.2 (1)
[0072] where HAr is a substituted or unsubstituted
nitrogen-containing heterocyclic group having 3 to 40 carbons;
[0073] L is a single bond, a substituted or unsubstituted arylene
group having 6 to 60 carbons, a substituted or unsubstituted
heteroarylene group having 3 to 60 carbons, or a substituted or
unsubstituted fluorenylene group;
[0074] Ar.sup.1 is a substituted or unsubstituted divalent aromatic
hydrocarbon group having 6 to 60 carbons; and
[0075] Ar.sup.2 is a substituted or unsubstituted aryl group having
6 to 60 carbons or a substituted or unsubstituted heteroaryl group
having 3 to 60 carbons.)
[0076] These materials allow an electron transporting layer having
an excellent electron transporting performance.
[0077] Incidentally, a third dopant may be doped to the host of the
emitting layer in addition to the first and second dopants.
BRIEF DESCRIPTION OF THE DRAWINGS
[0078] FIG. 1 shows an example of an organic electroluminescence
device according to an embodiment of the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT(S)
[0079] Embodiments of the present invention will be described
below.
[0080] FIG. 1 shows an example of an organic electroluminescence
device (hereafter abbreviated to OELD).
[0081] An OELD 1 constitutes a pixel of a display panel, and
voltage applied to the OELD 1 is controlled by a drive circuit (not
shown) to control light-emitting operation of the OELD 1.
[0082] The OELD 1 includes an anode 12, an organic layer 13, and a
cathode 14, which are layered in this order starting from a
substrate 11, and is covered by a protection film 15 to be
airtightly protected.
[0083] The embodiment is of a bottom emission type in which
emitting light is acquired from a side of the transparent glass
substrate 11, and a transparent electrode is provided as an anode
12 on the glass substrate 11.
[0084] Provided opposite to the anode 12 with the organic layer 13
inbetween is a light reflective cathode 14 made of Al or the
like.
[0085] A hole transporting zone 131, an emitting layer 132, and an
electron transporting zone 133 are provided to the organic layer 13
in this order starting from the side of the anode 12.
[0086] The hole transporting zone 131, which transports holes
injected from the anode 12 and injects the holes to the emitting
layer 132, is formed by a hole transporting layer 131A.
[0087] Ionization energy of the hole transporting layer 131A (the
hole transporting zone 131) may preferably be small. For example,
it is preferable that ionization energy normally be 5.5 eV or
less.
[0088] A material that transports holes at a lower electric
intensity is preferable for the hole transporting layer 131A (the
hole transporting zone 131). For example, it is preferable that the
rate be at least 10.sup.-4 cm.sup.2/Vsecond when an electric field
of 10.sup.4 to 10.sup.6 V/cm is applied. Specific materials will be
described later.
[0089] Holes and electrons are injected to the emitting layer 132
when an electric field is applied (electric charge injecting
function), the emitting layer 132 transports the injected electric
charge (the holes and the electrons) by force of electric field
(electric charge transporting function), and the emitting layer 132
provides a place for recombination of the holes and the electrons
and obtains light emission (light emitting function).
[0090] In the embodiment, a host, a first dopant, and a second
dopant are provided to the emitting layer 132.
[0091] A description on a host material and a dopant material will
be given below.
[0092] The emitting layer 132 includes the host material, which
constitutes most of the emitting layer 132, and the dopant
material, which is doped to the host material.
[0093] The host material occupies most (e.g. 80% or more) of the
emitting layer 132, which may, for example, be 30 nm to 100 nm
thick.
[0094] For example, a ratio at which the dopant material is doped
to the host material (the dopant material/the host material) is set
to be 0.01% to 20% by mass.
[0095] Energy transfer or the like from the host material to the
dopant material occurs, and the dopant material conducts light
emitting Hfunction.
[0096] In the embodiment, two kinds of dopants, the first dopant
and the second dopant, are doped to the host.
[0097] Most of light emission attributes to the first dopant, whose
luminous intensity I.sub.1 is twelve times larger than the luminous
intensity I.sub.2 of the second dopant.
[0098] In order to provide an OELD 1 that performs good shortwave
light emission, the first dopant that primarily emits light may be,
for example, a material that performs blue emission, and possesses,
for example, an energy gap of 2.9 eV or more.
[0099] The luminous intensity I.sub.2 of the second dopant, a small
amount of which is contained in the emitting layer 132, is low.
[0100] In order to provide a low luminous intensity I.sub.2 of the
second dopant, the second dopant is contained at an amount of 0.001
mass % to 0.5 mass % of the emitting layer 132.
[0101] The second dopant has a smaller energy gap than that of the
first dopant. If an energy gap of the first dopant is 2.9 eV or
more, an energy gap of the second gap is less than 2.9 eV.
[0102] In order to provide a second dopant that functions as an
electron trap, an affinity level Af.sub.2 of the second dopant is
larger than an affinity level Af.sub.H of the host by 0.2 eV or
more.
[0103] Next, a coating process is employed to form the emitting
layer 132 containing a small amount of the second dopant as
described above.
[0104] More specifically, the host material, the first dopant
material, and the second dopant material, each in a predetermined
amount, is dissolved in a solvent to provide an
organic-electroluminescent-material-containing solution.
[0105] A film is then formed of the solution on a base layer by
spin coating or the like.
[0106] When a coating method that uses a solution is employed, a
containing ratio of the three materials, that is, the host, the
first dopant, and the second dopant can be precisely
controlled.
[0107] In particular, the containing ratio of the small amount of
the second dopant can be precisely controlled, thus enabling
formation of a film in which the second dopant is evenly
dispersed.
[0108] Now, examples of compounds that constitute the emitting
layer 132 will be shown.
[0109] A material already known to possess a long life and light
emitting property can be used for the host.
[0110] For example, a material represented by the following formula
(2) may preferably be used for the host material.
##STR00001##
[0111] In the above formula (2), Ar.sup.1 represents an aromatic
ring whose number of carbon atoms forming the aromatic ring is 6 to
50 and X represents a substituent group.
[0112] The sign m refers to an integer from 1 to 5, and the sign n
refers to an integer from 0 to 6. If m.gtoreq.2, Ar.sup.1s can be
the same or different. If n.gtoreq.2, X can be the same or
different.
[0113] To be specific, Ar.sup.1 may be a phenyl ring, naphthyl
ring, anthracene ring, biphenylene ring, azulene ring,
acenaphthylene ring, fluorene ring, phenanthrene ring, fluoranthene
ring, acephenanthrylene ring, triphenylene ring, pyrene ring,
chrysene ring, naphthacene ring, picene ring, perylene ring,
pentaphene ring, pentacene ring, tetraphenylene ring, hexaphene
ring, hexacene ring, rubicene ring, coronene ring, trinaphthylene
ring, or the like.
[0114] Ar.sup.1 may preferably be a phenyl ring, naphthyl ring,
anthracene ring, acenaphthylene ring, fluorene ring, phenanthrene
ring, fluoranthene ring, triphenylene ring, pyrene ring, chrysene
ring, perylene ring, trinaphthylene ring, or the like.
[0115] Ar.sup.1 may further preferably be a phenyl ring, naphthyl
ring, anthracene ring, fluorene ring, phenanthrene ring,
fluoranthene ring, pyrene ring, chrysene ring, perylene ring, or
the like.
[0116] Also to be specific, X may be a substituted or unsubstituted
aromatic group having 6 to 50 ring carbon atoms, substituted or
unsubstituted aromatic heterocyclic group whose number of atoms
forming the aromatic ring is 5 to 50, substituted or unsubstituted
alkyl group having 1 to 50 carbons, substituted or unsubstituted
alkoxy group having 1 to 50 carbons, substituted or unsubstituted
aralkyl group having 1 to 50 carbons, substituted or unsubstituted
aryloxy group having 5 to 50 ring atoms, substituted or
unsubstituted arylthio group having 5 to 50 ring atoms, substituted
or unsubstituted carboxyl group having 1 to 50 carbons, substituted
or unsubstituted styryl group, halogen group, cyano group, nitro
group, hydroxyl group, or the like.
[0117] Examples of the substituted or unsubstituted aromatic group
having 6 to 50 ring carbon atoms are a phenyl group, 1-naphthyl
group, 2-naphthyl group, 1-anthryl group, 2-anthryl group,
9-anthryl group, 1-phenanthryl group, 2-phenanthryl group,
3-phenanthryl group, 4-phenanthryl group, 9-phenanthryl group,
1-naphthacenyl group, 2-naphthacenyl group, 9-naphthacenyl group,
1-pyrenyl group, 2-pyrenyl group, 4-pyrenyl group, 2-biphenylyl
group, 3-biphenylyl group, 4-biphenylyl group, p-terphenyl-4-yl
group, p-terphenyl-3-yl group, p-terphenyl-2-yl group,
m-terphenyl-4-yl group, m-terphenyl-3-yl-group, m-terphenyl-2-yl
group, o-tolyl group, m-tolyl group, p-tolyl group, p-t-butylphenyl
group, p-(2-phenylpropyl)phenyl group, 3-methyl-2-naphthyl group,
4-methyl-1-naphthyl group, 4-methyl-1-anthryl group,
4'-methylbiphenylyl group, 4''-t-butyl-p-terphenyl-4-yl group,
2-fluorenyl group, 9,9-dimethyl-2-fluorenyl group, 3-fluoranthenyl
group, and the like.
[0118] The substituted or unsubstituted aromatic group having 6 to
50 ring carbon atoms may preferably be a phenyl group, 1-naphthyl
group, 2-naphthyl group, 9-phenanthryl group, 1-naphthacenyl group,
2-naphthacenyl group, 9-naphthacenyl group, 1-pyrenyl group,
2-pyrenyl group, 4-pyrenyl group, 2-biphenylyl group, 3-biphenylyl
group, 4-biphenylyl group, o-tolyl group, m-tolyl group, p-tolyl
group, p-t-butylphenyl group, 2-fluorenyl group,
9,9-dimethyl-2-fluorenyl group, 3-fluoranthenyl group, or the
like.
[0119] Examples of the substituted or unsubstituted aromatic
heterocyclic group having 5 to 50 ring atoms include a 1-pyrrolyl
group, 2-pyrrolyl group, 3-pyrrolyl group, pyrazinyl group,
2-pyridinyl group, 3-pyridinyl group, 4-pyridinyl group, 1-indolyl
group, 2-indolyl group, 3-indolyl group, 4-indolyl group, 5-indolyl
group, 6-indolyl group, 7-indolyl group, 1-isoindolyl group,
2-isoindolyl group, 3-isoindolyl group, 4-isoindolyl group,
5-isoindolyl group, 6-isoindolyl group, 7-isoindolyl group, 2-furyl
group, 3-furyl group, 2-benzofuranyl group, 3-benzofuranyl group,
4-benzofuranyl group, 5-benzofuranyl group, 6-benzofuranyl group,
7-benzofuranyl group, 1-isobenzofuranyl group, 3-isobenzofuranyl
group, 4-isobenzofuranyl group, 5-isobenzofuranyl group,
6-isobenzofuranyl group, 7-isobenzofuranyl group, quinolyl group,
3-quinolyl group, 4-quinolyl group, 5-quinolyl group, 6-quinolyl
group, 7-quinolyl group, 8-quinolyl group, 1-isoquinolyl group,
3-isoquinolyl group, 4-isoquinolyl group, 5-isoquinolyl group,
6-isoquinolyl group, 7-isoquinolyl group, 8-isoquinolyl group,
2-quinoxalinyl group, 5-quinoxalinyl group, 6-quinoxalinyl group,
1-carbazolyl group, 2-carbazolyl group, 3-carbazolyl group,
4-carbazolyl group, 9-carbazolyl group, 1-phenanthridinyl group,
2-phenanthridinyl group, 3-phenanthridinyl group, 4-phenanthridinyl
group, 6-phenanthridinyl group, 7-phenanthridinyl group,
8-phenanthridinyl group, 9-phenanthridinyl group,
10-phenanthridinyl group, 1-acridinyl group, 2-acridinyl group,
3-acridinyl group, 4-acridinyl group, 9-acridinyl group,
1,7-phenanthrolin-2-yl group, 1,7-phenanthrolin-3-yl group,
1,7-phenanthrolin-4-yl group, 1,7-phenanthrolin-5-yl group,
1,7-phenanthrolin-6-yl group, 1,7-phenanthrolin-8-yl group,
1,7-phenanthrolin-9-yl group, 1,7-phenanthrolin-10-yl group,
1,8-phenanthrolin-2-yl group, 1,8-phenanthrolin-3-yl group,
1,8-phenanthrolin-4-yl group, 1,8-phenanthrolin-5-yl group,
1,8-phenanthrolin-6-yl group, 1,8-phenanthrolin-7-yl group,
1,8-phenanthrolin-9-yl group, 1,8-phenanthrolin-10-yl group,
1,9-phenanthrolin-2-yl group, 1,9-phenanthrolin-3-yl group,
1,9-phenanthrolin-4-yl group, 1,9-phenanthrolin-5-yl group,
1,9-phenanthrolin-6-yl group, 1,9-phenanthrolin-7-yl group,
1,9-phenanthrolin-8-yl group, 1,9-phenanthrolin-10-yl group,
1,10-phenanthrolin-2-yl group, 1,10-phenanthrolin-3-yl group,
1,10-phenanthrolin-4-yl group, 1,10-phenanthrolin-5-yl group,
2,9-phenanthrolin-1-yl group, 2,9-phenanthrolin-3-yl group,
2,9-phenanthrolin-4-yl group, 2,9-phenanthrolin-5-yl group,
2,9-phenanthrolin-6-yl group, 2,9-phenanthrolin-7-yl group,
2,9-phenanthrolin-8-yl group, 2,9-phenanthrolin-10-yl group,
2,8-phenanthrolin-1-yl group, 2,8-phenanthrolin-3-yl group,
2,8-phenanthrolin-4-yl group, 2,8-phenanthrolin-5-yl group,
2,8-phenanthrolin-6-yl group, 2,8-phenanthrolin-7-yl group,
2,8-phenanthrolin-9-yl group, 2,8-phenanthrolin-10-yl group,
2,7-phenanthrolin-1-yl group, 2,7-phenanthrolin-3-yl group,
2,7-phenanthrolin-4-yl group, 2,7-phenanthrolin-5-yl group,
2,7-phenanthrolin-6-yl group, 2,7-phenanthrolin-8-yl group,
2,7-phenanthrolin-9-yl group, 2,7-phenanthrolin-10-yl group,
1-phenazinyl group, 2-phenazinyl group, 1-phenothiazinyl group,
2-phenothiazinyl group, 3-phenothiazinyl group, 4-phenothiazinyl
group, 10-phenothiazinyl group, 1-phenoxazinyl group,
2-phenoxazinyl group, 3-phenoxazinyl group, 4-phenoxazinyl group,
10-phenoxazinyl group, 2-oxazolyl group, 4-oxazolyl group,
5-oxazolyl group, 2-oxadiazolyl group, 5-oxadiazolyl group,
3-furazanyl group, 2-thienyl group, 3-thienyl group,
2-methylpyrrol-1-yl group, 2-methylpyrrol-3-yl group,
2-methylpyrrol-4-yl group, 2-methylpyrrol-5-yl group,
3-methylpyrrol-1-yl group, 3-methylpyrrol-2-yl group,
3-methylpyrrol-4-yl group, 3-methylpyrrol-5-yl group,
2-t-butylpyrrol-4-yl group, 3-(2-phenylpropyl)pyrrol-1-yl group,
2-methyl-1-indolyl group, 4-methyl-1-indolyl group,
2-methyl-3-indolyl group, 4-methyl-3-indolyl group,
2-t-butyl-1-indolyl group, 4-t-butyl-1-indolyl group,
2-t-butyl-3-indolyl group, 4-t-butyl-3-indolyl group, and the
like.
[0120] Examples of the substituted or unsubstituted alkyl group
having 1 to 50 carbons include a methyl group, ethyl group, propyl
group, isopropyl group, n-butyl group, s-butyl group, isobutyl
group, t-butyl group, n-pentyl group, n-hexyl group, n-heptyl
group, n-octyl group, hydroxymethyl group, 1-hydroxyethyl group,
2-hydroxyethyl group, 2-hydroxyisobutyl group, 1,2-dihydroxyethyl
group, 1,3-dihydroxyisopropyl group, 2,3-dihydroxy-t-butyl group,
1,2,3-trihydroxypropyl group, chloromethyl group, 1-chloroethyl
group, 2-chloroethyl group, 2-chloroisobutyl group,
1,2-dichloroethyl group, 1,3-dichloroisopropyl group,
2,3-dichloro-t-butyl group, 1,2,3-trichloropropyl group,
bromomethyl group, 1-bromoethyl group, 2-bromoethyl group,
2-bromoisobutyl group, 1,2-dibromoethyl group, 1,3-dibromoisopropyl
group, 2,3-dibromo-t-butyl group, 1,2,3-tribromopropyl group,
iodomethyl group, 1-iodoethyl group, 2-iodoethyl group,
2-iodoisobutyl group, 1,2-diiodoethyl group, 1,3-diiodoisopropyl
group, 2,3-diiodo-t-butyl group, 1,2,3-triiodopropyl group,
aminomethyl group, 1-aminoethyl group, 2-aminoethyl group,
2-aminoisobutyl group, 1,2-diaminoethyl group, 1,3-diaminoisopropyl
group, 2,3-diamino-t-butyl group, 1,2,3-triaminopropyl group,
cyanomethyl group, 1-cyanoethyl group, 2-cyanoethyl group,
2-cyanoisobutyl group, 1,2-dicyanoethyl group, 1,3-dicyanoisopropyl
group, 2,3-dicyano-t-butyl group, 1,2,3-tricyanopropyl group,
nitromethyl group, 1-nitroethyl group, 2-nitroethyl group,
2-nitroisobutyl group, 1,2-dinitroethyl group, 1,3-dinitroisopropyl
group, 2,3-dinitro-t-butyl group, 1,2,3-trinitropropyl group,
cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl
group, 4-methylcyclohexyl group, 1-adamantyl group, 2-adamantyl
group, 1-norbornyl group, 2-norbornyl group, and the like.
[0121] The substituted or unsubstituted alkoxy group having 1 to 50
carbons is represented by --OY. Examples of Y include a methyl
group, ethyl group, propyl group, isopropyl group, n-butyl group,
s-butyl group, isobutyl group, t-butyl group, n-pentyl group,
n-hexyl group, n-heptyl group, n-octyl group, hydroxymethyl group,
1-hydroxyethyl group, 2-hydroxyethyl group, 2-hydroxyisobutyl
group, 1,2-dihydroxyethyl group, 1,3-dihydroxyisopropyl group,
2,3-dihydroxy-t-butyl group, 1,2,3-trihydroxypropyl group,
chloromethyl group, 1-chloroethyl group, 2-chloroethyl group,
2-chloroisobutyl group, 1,2-dichloroethyl group,
1,3-dichloroisopropyl group, 2,3-dichloro-t-butyl group,
1,2,3-trichloropropyl group, bromomethyl group, 1-bromoethyl group,
2-bromoethyl group, 2-bromoisobutyl group, 1,2-dibromoethyl group,
1,3-dibromoisopropyl group, 2,3-dibromo-t-butyl group,
1,2,3-tribromopropyl group, iodomethyl group, 1-iodoethyl group,
2-iodoethyl group, 2-iodoisobutyl group, 1,2-diiodoethyl group,
1,3-diiodoisopropyl group, 2,3-diiodo-t-butyl group,
1,2,3-triiodopropyl group, aminomethyl group, 1-aminoethyl group,
2-aminoethyl group, 2-aminoisobutyl group, 1,2-diaminoethyl group,
1,3-diaminoisopropyl group, 2,3-diamino-t-butyl group,
1,2,3-triaminopropyl group, cyanomethyl group, 1-cyanoethyl group,
2-cyanoethyl group, 2-cyanoisobutyl group, 1,2-dicyanoethyl group,
1,3-dicyanoisopropyl group, 2,3-dicyano-t-butyl group,
1,2,3-tricyanopropyl group, nitromethyl group, 1-nitroethyl group,
2-nitroethyl group, 2-nitroisobutyl group, 1,2-dinitroethyl group,
1,3-dinitroisopropyl group, 2,3-dinitro-t-butyl group,
1,2,3-trinitropropyl group, and the like.
[0122] Examples of the substituted or unsubstituted aralkyl group
having 1 to 50 carbons include benzyl group, 1-phenylethyl group,
2-phenylethyl group, 1-phenylisopropyl group, 2-phenylisopropyl
group, phenyl-t-butyl group, .alpha.-naphthylmethyl group,
1-.alpha.-naphthylethyl group, 2-.alpha.-naphthylethyl group,
1-.alpha.-naphthylisopropyl group, 2-.alpha.-naphthylisopropyl
group, .beta.-naphthylmethyl group, 1-.beta.-naphthylethyl group,
2-.beta.-naphthylethyl group, 1-.beta.-naphthylisopropyl group,
2-.beta.-naphthylisopropyl group, 1-pyrrolylmethyl group,
2-(1-pyrrolyl)ethyl group, p-methylbenzyl group, m-methylbenzyl
group, o-methylbenzyl group, p-chlorobenzyl group, m-chlorobenzyl
group, o-chlorobenzyl group, p-bromobenzyl group, m-bromobenzyl
group, o-bromobenzyl group, p-iodobenzyl group, m-iodobenzyl group,
o-iodobenzyl group, p-hydroxybenzyl group, m-hydroxybenzyl group,
o-hydroxybenzyl group, p-aminobenzyl group, m-aminobenzyl group,
o-aminobenzyl group, p-nitrobenzyl group, m-nitrobenzyl group,
o-nitrobenzyl group, p-cyanobenzyl group, m-cyanobenzyl group,
o-cyanobenzyl group, 1-hydroxy-2-phenylisopropyl group,
1-chloro-2-phenylisopropyl group and the like.
[0123] The substituted or unsubstituted aryloxy group having 5 to
50 ring atoms is represented by --OY'. Examples of Y' include a
phenyl group, 1-naphthyl group, 2-naphthyl group, 1-anthryl group,
2-anthryl group, 9-anthryl group, 1-phenanthryl group,
2-phenanthryl group, 3-phenanthryl group, 4-phenanthryl group,
9-phenanthryl group, 1-naphthacenyl group, 2-naphthacenyl group,
9-naphthacenyl group, 1-pyrenyl group, 2-pyrenyl group, 4-pyrenyl
group, 2-biphenylyl group, 3-biphenylyl group, 4-biphenylyl group,
p-terphenyl-4-yl group, p-terphenyl-3-yl group, p-terphenyl-2-yl
group, m-terphenyl-4-yl group, m-terphenyl-3-yl group,
m-terphenyl-2-yl group, o-tolyl group, m-tolyl group, p-tolyl
group, p-t-butylphenyl group, p-(2-phenylpropyl)phenyl group,
3-methyl-2-naphthyl group, 4-methyl-1-naphthyl group,
4-methyl-1-anthryl group, 4'-methylbiphenylyl group,
4''-t-butyl-p-terphenyl-4-yl group, 2-pyrrolyl group, 3-pyrrolyl
group, pyrazinyl group, 2-pyridinyl group, 3-pyridinyl group,
4-pyridinyl group, 2-indolyl group, 3-indolyl group, 4-indolyl
group, 5-indolyl group, 6-indolyl group, 7-indolyl group,
1-isoindolyl group, 3-isoindolyl group, 4-isoindolyl group,
5-isoindolyl group, 6-isoindolyl group, 7-isoindolyl group, 2-furyl
group, 3-furyl group, 2-benzofuranyl group, 3-benzofuranyl group,
4-benzofuranyl group, 5-benzofuranyl group, 6-benzofuranyl group,
7-benzofuranyl group, 1-isobenzofuranyl group, 3-isobenzofuranyl
group, 4-isobenzofuranyl group, 5-isobenzofuranyl group,
6-isobenzofuranyl group, 7-isobenzofuranyl group, 2-quinolyl group,
3-quinolyl group, 4-quinolyl group, 5-quinolyl group, 6-quinolyl
group, 7-quinolyl group, 8-quinolyl group, 1-isoquinolyl group,
3-isoquinolyl group, 4-isoquinolyl group, 5-isoquinolyl group,
6-isoquinolyl group, 7-isoquinolyl group, 8-isoquinolyl group,
2-quinoxalinyl group, 5-quinoxalinyl group, 6-quinoxalinyl group,
1-carbazolyl group, 2-carbazolyl group, 3-carbazolyl group,
4-carbazolyl group, 1-phenanthridinyl group, 2-phenanthridinyl
group, 3-phenanthridinyl group, 4-phenanthridinyl group,
6-phenanthridinyl group, 7-phenanthridinyl group, 8-phenanthridinyl
group, 9-phenanthridinyl group, 10-phenanthridinyl group,
1-acridinyl group, 2-acridinyl group, 3-acridinyl group,
4-acridinyl group, 9-acridinyl group, 1,7-phenanthrolin-2-yl group,
1,7-phenanthrolin-3-yl group, 1,7-phenanthrolin-4-yl group,
1,7-phenanthrolin-5-yl group, 1,7-phenanthrolin-6-yl group,
1,7-phenanthrolin-8-yl group, 1,7-phenanthrolin-9-yl group,
1,7-phenanthrolin-10-yl group, 1,8-phenanthrolin-2-yl group,
1,8-phenanthrolin-3-yl group, 1,8-phenanthrolin-4-yl group,
1,8-phenanthrolin-5-yl group, 1,8-phenanthrolin-6-yl group,
1,8-phenanthrolin-7-yl group, 1,8-phenanthrolin-9-yl group,
1,8-phenanthrolin-10-yl group, 1,9-phenanthrolin-2-yl group,
1,9-phenanthrolin-3-yl group, 1,9-phenanthrolin-4-yl group,
1,9-phenanthrolin-5-yl group, 1,9-phenanthrolin-6-yl group,
1,9-phenanthrolin-7-yl group, 1,9-phenanthrolin-8-yl group,
1,9-phenanthrolin-10-yl group, 1,10-phenanthrolin-2-yl group,
1,10-phenanthrolin-3-yl group, 1,10-phenanthrolin-4-yl group,
1,10-phenanthrolin-5-yl group, 2,9-phenanthrolin-1-yl group,
2,9-phenanthrolin-3-yl group, 2,9-phenanthrolin-4-yl group,
2,9-phenanthrolin-5-yl group, 2,9-phenanthrolin-6-yl group,
2,9-phenanthrolin-7-yl group, 2,9-phenanthrolin-8-yl group,
2,9-phenanthrolin-10-yl group, 2,8-phenanthrolin-1-yl group,
2,8-phenanthrolin-3-yl group, 2,8-phenanthrolin-4-yl group,
2,8-phenanthrolin-5-yl group, 2,8-phenanthrolin-6-yl group,
2,8-phenanthrolin-7-yl group, 2,8-phenanthrolin-9-yl group,
2,8-phenanthrolin-10-yl group, 2,7-phenanthrolin-1-yl group,
2,7-phenanthrolin-3-yl group, 2,7-phenanthrolin-4-yl group,
2,7-phenanthrolin-5-yl group, 2,7-phenanthrolin-6-yl group,
2,7-phenanthrolin-8-yl group, 2,7-phenanthrolin-9-yl group,
2,7-phenanthrolin-10-yl group, 1-phenazinyl group, 2-phenazinyl
group, 1-phenothiazinyl group, 2-phenothiazinyl group,
3-phenothiazinyl group, 4-phenothiazinyl group, 1-phenoxazinyl
group, 2-phenoxazinyl group, 3-phenoxazinyl group, 4-phenoxazinyl
group, 2-oxazolyl group, 4-oxazolyl group, 5-oxazolyl group,
2-oxadiazolyl group, 5-oxadiazolyl group, 3-furazanyl group,
2-thienyl group, 3-thienyl group, 2-methylpyrrol-1-yl group,
2-methylpyrrol-3-yl group, 2-methylpyrrol-4-yl group,
2-methylpyrrol-5-yl group, 3-methylpyrrol-1-yl group,
3-methylpyrrol-2-yl group, 3-methylpyrrol-4-yl group,
3-methylpyrrol-5-yl group, 2-t-butylpyrrol-4-yl group,
3-(2-phenylpropyl)pyrrol-1-yl group, 2-methyl-1-indolyl group,
4-methyl-1-indolyl group, 2-methyl-3-indolyl group,
4-methyl-3-indolyl group, 2-t-butyl-1-indolyl group,
4-t-butyl-1-indolyl group, 2-t-butyl-3-indolyl group,
4-t-butyl-3-indolyl group, and the like.
[0124] The substituted or unsubstituted arylthio group having 5 to
50 ring atoms is represented by --SY''. Examples of Y'' include a
phenyl group, 1-naphthyl group, 2-naphthyl group, 1-anthryl group,
2-anthryl group, 9-anthryl group, 1-phenanthryl group,
2-phenanthryl group, 3-phenanthryl group, 4-phenanthryl group,
9-phenanthryl group, 1-naphthacenyl group, 2-naphthacenyl group,
9-naphthacenyl group, 1-pyrenyl group, 2-pyrenyl group, 4-pyrenyl
group, 2-biphenylyl group, 3-biphenylyl group, 4-biphenylyl group,
p-terphenyl-4-yl group, p-terphenyl-3-yl group, p-terphenyl-2-yl
group, m-terphenyl-4-yl group, m-terphenyl-3-yl group,
m-terphenyl-2-yl group, o-tolyl group, m-tolyl group, p-tolyl
group, p-t-butylphenyl group, p-(2-phenylpropyl)phenyl group,
3-methyl-2-naphthyl group, 4-methyl-1-naphthyl group,
4-methyl-1-anthryl group, 4'-methylbiphenylyl group,
4''-t-butyl-p-terphenyl-4-yl group, 2-pyrrolyl group, 3-pyrrolyl
group, pyrazinyl group, 2-pyridinyl group, 3-pyridinyl group,
4-pyridinyl group, 2-indolyl group, 3-indolyl group, 4-indolyl
group, 5-indolyl group, 6-indolyl group, 7-indolyl group,
1-isoindolyl group, 3-isoindolyl group, 4-isoindolyl group,
5-isoindolyl group, 6-isoindolyl group, 7-isoindolyl group, 2-furyl
group, 3-furyl group, 2-benzofuranyl group, 3-benzofuranyl group,
4-benzofuranyl group, 5-benzofuranyl group, 6-benzofuranyl group,
7-benzofuranyl group, 1-isobenzofuranyl group, 3-isobenzofuranyl
group, 4-isobenzofuranyl group, 5-isobenzofuranyl group,
6-isobenzofuranyl group, 7-isobenzofuranyl group, 2-quinolyl group,
3-quinolyl group, 4-quinolyl group, 5-quinolyl group, 6-quinolyl
group, 7-quinolyl group, 8-quinolyl group, 1-isoquinolyl group,
3-isoquinolyl group, 4-isoquinolyl group, 5-isoquinolyl group,
6-isoquinolyl group, 7-isoquinolyl group, 8-isoquinolyl group,
2-quinoxalinyl group, 5-quinoxalinyl group, 6-quinoxalinyl group,
1-carbazolyl group, 2-carbazolyl group, 3-carbazolyl group,
4-carbazolyl group, 1-phenanthridinyl group, 2-phenanthridinyl
group, 3-phenanthridinyl group, 4-phenanthridinyl group,
6-phenanthridinyl group, 7-phenanthridinyl group, 8-phenanthridinyl
group, 9-phenanthridinyl group, 10-phenanthridinyl group,
1-acridinyl group, 2-acridinyl group, 3-acridinyl group,
4-acridinyl group, 9-acridinyl group, 1,7-phenanthrolin-2-yl group,
1,7-phenanthrolin-3-yl group, 1,7-phenanthrolin-4-yl group,
1,7-phenanthrolin-5-yl group, 1,7-phenanthrolin-6-yl group,
1,7-phenanthrolin-8-yl group, 1,7-phenanthrolin-9-yl group,
1,7-phenanthrolin-10-yl group, 1,8-phenanthrolin-2-yl group,
1,8-phenanthrolin-3-yl group, 1,8-phenanthrolin-4-yl group,
1,8-phenanthrolin-5-yl group, 1,8-phenanthrolin-6-yl group,
1,8-phenanthrolin-7-yl group, 1,8-phenanthrolin-9-yl group,
1,8-phenanthrolin-10-yl group, 1,9-phenanthrolin-2-yl group,
1,9-phenanthrolin-3-yl group, 1,9-phenanthrolin-4-yl group,
1,9-phenanthrolin-5-yl group, 1,9-phenanthrolin-6-yl group,
1,9-phenanthrolin-7-yl group, 1,9-phenanthrolin-8-yl group,
1,9-phenanthrolin-10-yl group, 1,10-phenanthrolin-2-yl group,
1,10-phenanthrolin-3-yl group, 1,10-phenanthrolin-4-yl group,
1,10-phenanthrolin-5-yl group, 2,9-phenanthrolin-1-yl group,
2,9-phenanthrolin-3-yl group, 2,9-phenanthrolin-4-yl group,
2,9-phenanthrolin-5-yl group, 2,9-phenanthrolin-6-yl group,
2,9-phenanthrolin-7-yl group, 2,9-phenanthrolin-8-yl group,
2,9-phenanthrolin-10-yl group, 2,8-phenanthrolin-1-yl group,
2,8-phenanthrolin-3-yl group, 2,8-phenanthrolin-4-yl group,
2,8-phenanthrolin-5-yl group, 2,8-phenanthrolin-6-yl group,
2,8-phenanthrolin-7-yl group, 2,8-phenanthrolin-9-yl group,
2,8-phenanthrolin-10-yl group, 2,7-phenanthrolin-1-yl group,
2,7-phenanthrolin-3-yl group, 2,7-phenanthrolin-4-yl group,
2,7-phenanthrolin-5-yl group, 2,7-phenanthrolin-6-yl group,
2,7-phenanthrolin-8-yl group, 2,7-phenanthrolin-9-yl group,
2,7-phenanthrolin-10-yl group, 1-phenazinyl group, 2-phenazinyl
group, 1-phenothiazinyl group, 2-phenothiazinyl group,
3-phenothiazinyl group, 4-phenothiazinyl group, 1-phenoxazinyl
group, 2-phenoxazinyl group, 3-phenoxazinyl group, 4-phenoxazinyl
group, 2-oxazolyl group, 4-oxazolyl group, 5-oxazolyl group,
2-oxadiazolyl group, 5-oxadiazolyl group, 3-furazanyl group,
2-thienyl group, 3-thienyl group, 2-methylpyrrol-1-yl group,
2-methylpyrrol-3-yl group, 2-methylpyrrol-4-yl group,
2-methylpyrrol-5-yl group, 3-methylpyrrol-1-yl group,
3-methylpyrrol-2-yl group, 3-methylpyrrol-4-yl group,
3-methylpyrrol-5-yl group, 2-t-butylpyrrol-4-yl group,
3-(2-phenylpropyl)pyrrol-1-yl group, 2-methyl-1-indolyl group,
4-methyl-1-indolyl group, 2-methyl-3-indolyl group,
4-methyl-3-indolyl group, 2-t-butyl-1-indolyl group,
4-t-butyl-1-indolyl group, 2-t-butyl-3-indolyl group,
4-t-butyl-3-indolyl group, and the like.
[0125] The substituted or unsubstituted carboxyl group having 1 to
50 carbons is represented by --COOZ. Examples of Z include a methyl
group, ethyl group, propyl group, isopropyl group, n-butyl group,
s-butyl group, isobutyl group, t-butyl group, n-pentyl group,
n-hexyl group, n-heptyl group, n-octyl group, hydroxymethyl group,
1-hydroxyethyl group, 2-hydroxyethyl group, 2-hydroxyisobutyl
group, 1,2-dihydroxyethyl group, 1,3-dihydroxyisopropyl group,
2,3-dihydroxy-t-butyl group, 1,2,3-trihydroxypropyl group,
chloromethyl group, 1-chloroethyl group, 2-chloroethyl group,
2-chloroisobutyl group, 1,2-dichloroethyl group,
1,3-dichloroisopropyl group, 2,3-dichloro-t-butyl group,
1,2,3-trichloropropyl group, bromomethyl group, 1-bromoethyl group,
2-bromoethyl group, 2-bromoisobutyl group, 1,2-dibromoethyl group,
1,3-dibromoisopropyl group, 2,3-dibromo-t-butyl group,
1,2,3-tribromopropyl group, iodomethyl group, 1-iodoethyl group,
2-iodoethyl group, 2-iodoisobutyl group, 1,2-diiodoethyl group,
1,3-diiodoisopropyl group, 2,3-diiodo-t-butyl group,
1,2,3-triiodopropyl group, aminomethyl group, 1-aminoethyl group,
2-aminoethyl group, 2-aminoisobutyl group, 1,2-diaminoethyl group,
1,3-diaminoisopropyl group, 2,3-diamino-t-butyl group,
1,2,3-triaminopropyl group, cyanomethyl group, 1-cyanoethyl group,
2-cyanoethyl group, 2-cyanoisobutyl group, 1,2-dicyanoethyl group,
1,3-dicyanoisopropyl group, 2,3-dicyano-t-butyl group,
1,2,3-tricyanopropyl group, nitromethyl group, 1-nitroethyl group,
2-nitroethyl group, 2-nitroisobutyl group, 1,2-dinitroethyl group,
1,3-dinitroisopropyl group, 2,3-dinitro-t-butyl group,
1,2,3-trinitropropyl group, and the like.
[0126] Examples of the substituted or unsubstituted styryl group
include a 2-phenyl-1-vinyl group, 2,2-diphenyl-1-vinyl group,
1,2,2-triphenyl-1-vinyl group, and the like.
[0127] Examples of the halogen group include fluorine, chlorine,
bromine, iodine, and the like.
[0128] 1 or 2 is preferable for m, and one of 0 to 4 is preferable
for n.
[0129] Specific examples of the above general formula (2) will be
shown below.
##STR00002## ##STR00003## ##STR00004## ##STR00005##
##STR00006##
[0130] An anthracene derivative represented by the following
formula (3) is also suitable for the host.
##STR00007##
[0131] In the above formula (3), each of R.sup.11 to R.sup.20
independently represents a hydrogen atom, alkyl group, cycloalkyl
group, aryl group, alkoxyl group aryloxy group, alkylamino group,
arylamino group or substitutable heterocyclic group. When c, d, e,
and f, each of which represents an integer from 1 to 5, are 2 or
larger: each of a plurality of R.sup.11 may be identical to or
different from each other, each of a plurality of R.sup.12 may be
identical to or different from each other, each of a plurality of
R.sup.16 may be identical to or different from each other, and each
of a plurality of R.sup.17 may be identical to or different from
each other; each of the plurality of R.sup.11 may combine with each
other to form a ring, each of the plurality of R.sup.12 may combine
with each other to form a ring, each of the plurality of R.sup.16
may combine with each other to form a ring, and each of the
plurality of R.sup.17 may combine with each other to form a ring;
and R.sup.13 and R.sup.14 may combine with each other to form a
ring, and R.sup.18 and R.sup.19 may combine with each other to form
a ring.
[0132] L.sup.2 represents a single bond, --O--, --S--, --N(R)-- (R
is an alkyl group or substitutable aryl group), alkylene group, or
arylene group.
[0133] A spirofluorene derivative represented by the following
formula (4) is also suitable for the host.
##STR00008##
[0134] In the above formula (4), each of A.sup.5 to A.sup.8 is
independently a substituted or unsubstituted biphenyl group or
substituted or unsubstituted naphthyl group.
[0135] Condensed-ring-containing compound represented by the
following formula (5) is also suitable for the host.
##STR00009##
[0136] In the above formula (5), each of A.sup.9 to A.sup.14
represents a hydrogen atom or substituted or unsubstituted aryl
group having 6 to 50 ring carbon atoms. Each of R.sup.21 to
R.sup.23 independently represents a hydrogen atom, alkyl group
having 1 to 6 carbons, cycloalkyl group having 3 to 6 carbons,
alkoxyl group having 1 to 6 carbons, aryloxy group having 5 to 18
carbons, aralkyloxy group having 7 to 18 carbons, arylamino group
having 5 to 16 carbons, nitro group, cyano group, ether group
having 1 to 6 carbons, or halogen atom. At least one of A.sup.9 to
A.sup.14 is a group having three or more condensed aromatic
rings.
[0137] A fluorene compound represented by the following formula (6)
is also suitable for the host.
##STR00010##
[0138] In the above formula (6), R.sub.1 and R.sub.2 represent a
hydrogen atom, substituted or unsubstituted alkyl group,
substituted or unsubstituted aralkyl group, substituted or
unsubstituted aryl group, substituted or unsubstituted heterocyclic
group, substituted amino group, cyano group, or halogen atom.
[0139] A plurality of R.sub.1 that bond with different fluorene
groups may be identical to or different from each other, a
plurality of R.sub.2 that bond with different fluorine groups may
be identical to or different from each other, and R.sub.1 and
R.sub.2 that bond with the same fluorene group may be identical to
or different from each other. R.sub.3 and R.sub.4 represent a
hydrogen atom, substituted or unsubstituted alkyl group,
substituted or unsubstituted aralkyl group, substituted or
unsubstituted aryl group, or substituted or unsubstituted
heterocyclic ring. A plurality of R.sub.3 that bond with different
fluorene groups may be identical to or different from each other, a
plurality of R.sub.4 that bond with different fluorene groups may
be identical to or different from each other, and R.sub.3 and
R.sub.4 that bond with the same fluorene group may be identical to
or different from each other. Ar.sub.1 and Ar.sub.2 represent a
substituted or unsubstituted condensed polycyclic aromatic group
that has three or more benzene rings or condensed polycyclic
heterocyclic group that has a total of three or more benzene rings
and heterocyclic rings and bonds with fluorene group by substituted
or unsubstituted carbons. Ar.sub.1 and Ar.sub.2 may be identical to
or different from each other. The sign n refers to an integer from
1 to 10.
[0140] Of the above host materials, anthracene derivative is
preferable, monoanthracene derivative is further preferable, and
asymmetric anthracene, in which left and right sides of anthracene
skeleton are different from each other, is especially
preferable.
[0141] A naphthacene derivative represented by the following
formula (7) is also suitable for the host.
##STR00011##
[0142] In the above formula (7), each of Q.sup.10, Q.sup.20,
Q.sup.30, Q.sup.40, Q.sup.50, Q.sup.60, Q.sup.70, Q.sup.80,
Q.sup.110, Q.sup.120, Q.sup.130, and Q.sup.140 represents a
hydrogen, alkyl group having 1 to 20 carbons, aryl group having 1
to 20 carbons, amino group, alkoxy group having 1 to 20 carbons,
alkylthio group having 1 to 20 carbons, aryloxy group having 1 to
20 carbons, arylthio group having 1 to 20 carbons, alkenyl group
having 1 to 20 carbons, aralkyl group having 1 to 20 carbons, or
heterocyclic group, and may be identical to or different from each
other.
[0143] One or more of Q.sup.10, Q.sup.20, Q.sup.30 and Q.sup.40 in
the naphthacene derivative represented by the above formula (7) may
preferably be an aryl group, and may further preferably be
represented by the following formula (8).
##STR00012##
[0144] In the above formula (8), each of Q.sup.10, Q.sup.21 to
Q.sup.25, Q.sup.31 to Q.sup.35, Q.sup.40 to Q.sup.80, and Q.sup.110
to Q.sup.140 may be a hydrogen, alkyl group, aryl group, amino
group, alkoxy group, aryloxy group, alkylthio group, arylthio
group, alkenyl group, aralkyl group, and heterocyclic group, and
may be identical to or different from each other.
[0145] Adjacent two or more of Q.sup.21 to Q.sup.25 and Q.sup.31 to
Q.sup.35 may bond with each other to form a ring.
[0146] One or more of Q.sup.21, Q.sup.25, Q.sup.31, and Q.sup.35 in
the naphthacene derivative may preferably be an alkyl group, aryl
group, amino group, alkoxy group, alkylthio group, aryloxy group,
arylthio group, alkenyl group, aralkyl group, and heterocyclic
group.
[0147] A fluoranthene derivative represented by the following
formula (9) is also suitable for the host.
##STR00013##
[0148] In the above formula (9), Ar represents a substituted or
unsubstituted aromatic group having 6 to 50 ring carbon atoms. The
plurality of R may be different from each other, and each of the
plurality of R independently is a hydrogen atom, substituted or
unsubstituted aromatic group having 6 to 50 ring carbon atoms,
substituted or unsubstituted aromatic heterocyclic group having 5
to 50 ring atoms, or substituted or unsubstituted alkyl group
having 1 to 50 carbons.
[0149] The following are specific examples of the above
fluoranthene derivative.
##STR00014##
[0150] R in the above formulae (10) and (11) is the same as R in
the above formula (9).
[0151] It is preferable that R be a hydrogen or phenyl group.
[0152] It is further preferable that two of R which substitute on
opposing sides of a naphthalene skeleton or anthracene skeleton be
a phenyl group and the rest of R be a hydrogen.
[0153] Next, a material already known to possess a long life and
light emitting property can be used for the first dopant and the
second dopant.
[0154] Concentrations of such a first dopant and such a second
dopant are determined so that luminous intensity I.sub.1 of the
first dopant is twelve times as great as that of the second dopant
or greater and the content of the second dopant is 0.001% to 0.5%
by mass.
[0155] In this case, the one with smaller energy gap is selected as
the second dopant so that the second dopant serves as an electric
charge trap.
[0156] Further, in view of providing a blue emitting material
having a longer lifetime, it is preferable that a material in which
Eg.gtoreq.2.9 eV be selected as the first dopant and the second
dopant be added to extend the life of the blue material (i.e. the
first dopant).
[0157] Dopant materials suitable for combining with the host
materials described above will be listed below, from which the
first dopant and second dopant are appropriately selected.
[0158] An amine dopant represented by the following formula is
suitable for the dopant.
##STR00015##
[0159] In the above formula (12), Ar.sup.2 to Ar.sup.4 are a
substituted or unsubstituted aromatic group having 6 to 50 ring
carbon atoms or substituted or unsubstituted styryl group.
[0160] The sign p refers to an integer from 1 to 4.
[0161] If p.gtoreq.2, each of Ar.sup.3 may be identical to or
different from each other, and each of Ar.sup.4 may be identical to
or different from each other.
[0162] Examples of the substituted or unsubstituted aromatic group
having 6 to 50 ring carbon atoms include a phenyl group, 1-naphthyl
group, 2-naphthyl group, 1-anthryl group, 2-anthryl group,
9-anthryl group, 1-phenanthryl group, 2-phenanthryl group,
3-phenanthryl group, 4-phenanthryl group, 9-phenanthryl group,
1-naphthacenyl group, 2-naphthacenyl group, 9-naphthacenyl group,
1-pyrenyl group, 2-pyrenyl group, 4-pyrenyl group, 2-biphenylyl
group, 3-biphenylyl group, 4-biphenylyl group, p-terphenyl-4-yl
group, p-terphenyl-3-yl group, p-terphenyl-2-yl group,
m-terphenyl-4-yl group, m-terphenyl-3-yl-group, m-terphenyl-2-yl
group, o-tolyl group, m-tolyl group, p-tolyl group, p-t-butylphenyl
group, p-(2-phenylpropyl)phenyl group, 3-methyl-2-naphthyl group,
4-methyl-1-naphthyl group, 4-methyl-1-anthryl group,
4'-methylbiphenylyl group, 4''-t-butyl-p-terphenyl-4-yl group,
2-fluorenyl group, 9,9-dimethyl-2-fluorenyl group, 3-fluoranthenyl
group, and the like.
[0163] A phenyl group, 1-naphthyl group, 2-naphthyl group,
9-phenanthryl group, 1-naphthacenyl group, 2-naphthacenyl group,
9-naphthacenyl group, 1-pyrenyl group, 2-pyrenyl group, 4-pyrenyl
group, 2-biphenylyl group, 3-biphenylyl group, 4-biphenylyl group,
o-tolyl group, m-tolyl group, p-tolyl group, p-t-butylphenyl group,
2-fluorenyl group, 9,9-dimethyl-2-fluorenyl group, 3-fluoranthenyl
group, or the like is preferable.
[0164] Examples of the substituted or unsubstituted styryl group
include a 2-phenyl-1-vinyl group, 2,2-diphenyl-1-vinyl group,
1,2,2-triphenyl-1-vinyl group, and the like.
[0165] Specific examples of the general formula (12) and examples
of other compounds suitable for the dopant will be shown below.
[0166] Note that in the formula, Me represents a methyl group and
Et represents an ethyl group.
[0167] The substituted styryl group is not limited to one in which
the styryl group and N are directly bonded, but also includes one
in which a divalent group (e.g. an arylene group, typically a
phenylene group, or the like) are provided between the styryl group
and N.
##STR00016## ##STR00017## ##STR00018##
[0168] The following is capable for use as the first dopant, but
rather suitable for use as the second dopant.
##STR00019## ##STR00020## ##STR00021## ##STR00022## ##STR00023##
##STR00024## ##STR00025## ##STR00026## ##STR00027## ##STR00028##
##STR00029##
[0169] Perylene derivatives of the following formulae (13) and (14)
are suitable for the second dopant, and especially suitable for
combining with the host of the above-described naphthacene
derivative.
##STR00030##
[0170] In the above general formulae (13) and (14), each of
Ar.sup.51, Ar.sup.52, and Ar.sup.53 independently represents a
substituted or unsubstituted aromatic hydrocarbon group having 6 to
50 ring carbon atoms or substituted or unsubstituted aromatic
heterocylic group having 6 to 50 ring atoms.
[0171] Each of X.sup.1 to X.sup.18 independently represents a group
selected from a hydrogen atom, halogen atom, substituted or
unsubstituted alkyl group having 1 to 50 carbons, substituted or
unsubstituted alkoxy group having 1 to 50 carbons, substituted or
unsubstituted alkylthio group having 1 to 50 carbons, substituted
or unsubstituted alkenyl group having 2 to 50 carbons, substituted
or unsubstituted alkenyloxy group having 1 to 50 carbons,
substituted or unsubstituted alkenylthio group having 1 to 50
carbons, substituted or unsubstituted aromatic hydrocarbon group
having 6 to 50 ring carbon atoms, substituted or unsubstituted
aromatic heterocyclic group having 6 to 50 ring atoms, substituted
or unsubstituted aryloxy group having 6 to 50 ring carbon atoms,
substituted or unsubstituted arylthio group having 6 to 50 ring
carbon atoms, substituted or unsubstituted aralkyl group having 7
to 50 ring carbon atoms, substituted or unsubstituted arylalkyloxy
group having 6 to 50 ring carbon atoms, substituted or
unsubstituted arylalkylthio group having 6 to 50 ring carbon atoms,
substituted or unsubstituted arylalkenyl group having 6 to 50 ring
carbon atoms, substituted or unsubstituted alkenylaryl group having
6 to 50 ring carbon atoms, amino group, carbazolyl group, cyano
group, hydroxyl group, --COOR.sup.54, --COR.sup.55, or
--OCOR.sup.56 (in which each of R.sup.54, R.sup.55, or R.sup.56
represents a hydrogen atom, substituted or unsubstituted alkyl
group having 1 to 50 carbons, substituted or unsubstituted alkenyl
group having 2 to 50 carbons, substituted or unsubstituted aralkyl
group having 7 to 50 ring carbon atoms, substituted or
unsubstituted aromatic hydrocarbon group having 6 to 50 ring carbon
atoms, and aromatic heterocyclic group having 6 to 50 ring
atoms).
[0172] Adjacent groups may bond with each other, and further may
form a ring together with carbon atoms to which X.sup.1 to X.sup.18
are bonded.
[0173] Here, in the above formulae (13) and (14), it is preferable
that at least one of X.sup.1 to X.sup.18 not be hydrogen or at
least one of the substituent groups Ar.sup.51, Ar.sup.52, and
Ar.sup.53, X.sup.1 to X.sup.18, and the substituent groups of
X.sup.1 to X.sup.18 be a halogen atom.
[0174] Of the perylene derivatives, an indenoperylene derivative
will be shown below.
##STR00031##
[0175] In the above formulae (15) and (16), each of R, which may be
different from each other, independently is a hydrogen atom,
halogen atom, alkyl group, alkoxy group, alkylthio group, alkenyl
group, alkenyloxy group, alkenylthio group,
aromatic-ring-containing alkyl group, aromatic-ring-containing
alkyloxy group, aromatic-ring-containing alkylthio group, aromatic
ring group, aromatic ring heterocyclic group, aromatic ring oxy
group, aromatic ring thio group, aromatic ring alkenyl group,
alkenyl aromatic ring group, amino group, carbazolyl group, cyano
group, hydroxyl group, --COOR.sup.51 (in which R.sup.51 is
hydrogen, alkyl group, alkenyl group, aromatic-ring-containing
alkyl group, or aromatic ring group), --COR.sup.52 (R.sup.52 is a
hydrogen, alkyl group, alkenyl group, aromatic-ring-containing
alkyl group, aromatic ring group, or amino group), or --OCOR.sup.53
(R.sup.53 is an alkyl group, alkenyl group,
aromatic-ring-containing alkyl group, or aromatic ring group).
[0176] Here, groups adjacent to R may bond with each other, or may
form a ring together with substituted carbon atoms.
[0177] Further, it is preferable that at least one of R not be
hydrogen.
[0178] Other than the ones described above, the dopant may be, but
is not limited to, a naphthalene derivative, anthracene derivative,
perylene derivative, pyrene derivative, naphthacene derivative,
rubrene derivative, fluoranthene derivative, benzofluoranthene
derivative, diindenoperylene derivative, styrylamine derivative,
bisamino-distilbene derivative, acridone derivative, acridine
derivative, quinacridone derivative, coumalin derivative (e.g.
coumalin 1, coumalin 6, coumalin 7, coumalin 30, coumalin 106,
coumalin 138, coumalin 151, coumalin 152, coumalin 153, coumalin
307, coumalin 311, coumalin 314, coumalin 334, coumalin 338,
coumalin 343, coumalin 500), pyrane derivative (e.g. DCM1, DCM2),
oxazone derivative (e.g. Nile Red), arylamine compound and/or
styrylamine compound, coronene, chrysene, fluoresceine,
phthaloperylene, naphthaloperylene, perynone, phthaloperynone,
naphthaloperynone, diphenylbutadiene, tetraphenylbutadiene,
oxadiazole, aldazine, bisbenzoxazoline, bisstyryl, pyrazine,
cyclopentadiene, metal complex of quinoline, metal complex of
aminoquinolin, metal complex of benzoquinoline, imine,
diphenylethylene, vinylanthracene, diaminocarbazole, pyrane,
thiopyrane, polymethine, merocyanine, chelate of oxinoid compound
with imidazole, fluorescent pigment, or the like.
[0179] The electron transporting zone 133 will be described
next.
[0180] The electron transporting zone 133 includes an electron
transporting layer 133A and an electron injecting layer 133B.
[0181] The electron transporting layer 133A, which facilitates
injection of an electron to the emitting layer 132, has high
electron mobility.
[0182] In the embodiment, in order to lower drive voltage, the
electron transporting layer 133A preferably possesses high electron
mobility, namely, electron mobility of 10.sup.-4 cm.sup.2/Vs or
more in the case of applying an electric field of 0.25 mV/cm.
[0183] If the electron transporting layer 133A having high electron
mobility as have mentioned is employed, the drive voltage is
decreased. On the other hand, excessive injection of electrons into
the emitting layer 132 may shorten lifetime.
[0184] In the embodiment, with regard to the problem, the second
dopant is doped to the emitting layer 132 so that the second dopant
serves as an electron trap, thus providing electric charge balance
in the embodiment.
[0185] Therefore, the electron transporting layer 133A having high
electron mobility is provided to achieve low drive voltage and a
long lifetime at the same time.
[0186] Also, it is known that light emission acquired directly from
the anode 12 and light emission acquired via reflection to the
electrode interfere with each other in a bottom emission type OELD
like the one in the embodiment.
[0187] In order to take advantage of this interference effect, the
electron transporting layer 133A is appropriately adjusted between
several nm to several .mu.m.
[0188] In this case, thickening of the electron transporting layer
133A may cause increase in the voltage etc. However, since the
electron transporting layer 133A having high electron mobility is
provided in the embodiment, thickening the layer to an extent where
the interfering effect can fully be made use of does not
necessarily lead to increase in the drive voltage.
[0189] Specific compounds for the electron transporting layer 133A
is exemplified by a nitrogen-containing heterocyclic derivative
represented by the above formula (1), and specific examples of the
nitrogen-containing heterocyclic derivative include the following.
Note that materials for the electron transporting layer of the
present invention are not limited to the following compounds, which
are shown as examples.
TABLE-US-00001 HAr--L--Ar.sup.1--Ar.sup.2 HAr L Ar.sup.1 Ar.sup.2
1-1 ##STR00032## ##STR00033## ##STR00034## ##STR00035## 2
##STR00036## ##STR00037## ##STR00038## ##STR00039## 3 ##STR00040##
##STR00041## ##STR00042## ##STR00043## 4 ##STR00044## ##STR00045##
##STR00046## ##STR00047## 5 ##STR00048## ##STR00049## ##STR00050##
##STR00051## 6 ##STR00052## ##STR00053## ##STR00054## ##STR00055##
7 ##STR00056## ##STR00057## ##STR00058## ##STR00059## 8
##STR00060## ##STR00061## ##STR00062## ##STR00063## 9 ##STR00064##
##STR00065## ##STR00066## ##STR00067## 10 ##STR00068## ##STR00069##
##STR00070## ##STR00071## 11 ##STR00072## ##STR00073## ##STR00074##
##STR00075## 12 ##STR00076## ##STR00077## ##STR00078## ##STR00079##
13 ##STR00080## ##STR00081## ##STR00082## ##STR00083## 14
##STR00084## ##STR00085## ##STR00086## ##STR00087## 2-1
##STR00088## ##STR00089## ##STR00090## ##STR00091## 2 ##STR00092##
##STR00093## ##STR00094## ##STR00095## 3 ##STR00096## ##STR00097##
##STR00098## ##STR00099## 4 ##STR00100## ##STR00101## ##STR00102##
##STR00103## 5 ##STR00104## ##STR00105## ##STR00106## ##STR00107##
6 ##STR00108## ##STR00109## ##STR00110## ##STR00111## 7
##STR00112## ##STR00113## ##STR00114## ##STR00115## 8 ##STR00116##
##STR00117## ##STR00118## ##STR00119## 9 ##STR00120## ##STR00121##
##STR00122## ##STR00123## 3-1 ##STR00124## ##STR00125##
##STR00126## ##STR00127## 2 ##STR00128## ##STR00129## ##STR00130##
##STR00131## 3 ##STR00132## ##STR00133## ##STR00134## ##STR00135##
4 ##STR00136## ##STR00137## ##STR00138## ##STR00139## 5
##STR00140## ##STR00141## ##STR00142## ##STR00143## 6 ##STR00144##
##STR00145## ##STR00146## ##STR00147## 4-1 ##STR00148##
##STR00149## ##STR00150## ##STR00151## 2 ##STR00152## ##STR00153##
##STR00154## ##STR00155## 3 ##STR00156## ##STR00157## ##STR00158##
##STR00159## 4 ##STR00160## ##STR00161## ##STR00162## ##STR00163##
5 ##STR00164## ##STR00165## ##STR00166## ##STR00167## 6
##STR00168## ##STR00169## ##STR00170## ##STR00171## 7 ##STR00172##
##STR00173## ##STR00174## ##STR00175## 8 ##STR00176## ##STR00177##
##STR00178## ##STR00179## 9 ##STR00180## ##STR00181## ##STR00182##
##STR00183## 10 ##STR00184## ##STR00185## ##STR00186## ##STR00187##
11 ##STR00188## ##STR00189## ##STR00190## ##STR00191## 12
##STR00192## ##STR00193## ##STR00194## ##STR00195## 5-1
##STR00196## ##STR00197## ##STR00198## ##STR00199## 2 ##STR00200##
##STR00201## ##STR00202## ##STR00203## 3 ##STR00204## ##STR00205##
##STR00206## ##STR00207## 4 ##STR00208## ##STR00209## ##STR00210##
##STR00211## 5 ##STR00212## ##STR00213## ##STR00214## ##STR00215##
6 ##STR00216## ##STR00217## ##STR00218## ##STR00219## 6-1
##STR00220## ##STR00221## ##STR00222## ##STR00223## 2 ##STR00224##
##STR00225## ##STR00226## ##STR00227## 3 ##STR00228## ##STR00229##
##STR00230## ##STR00231## 4 ##STR00232## ##STR00233## ##STR00234##
##STR00235## 5 ##STR00236## ##STR00237## ##STR00238## ##STR00239##
7-1 ##STR00240## ##STR00241## ##STR00242## ##STR00243## 2
##STR00244## ##STR00245## ##STR00246## ##STR00247## 3 ##STR00248##
##STR00249## ##STR00250## ##STR00251## 4 ##STR00252## ##STR00253##
##STR00254## ##STR00255## 5 ##STR00256## ##STR00257## ##STR00258##
##STR00259## 6 ##STR00260## ##STR00261## ##STR00262## ##STR00263##
7 ##STR00264## ##STR00265## ##STR00266## ##STR00267## 8
##STR00268## ##STR00269## ##STR00270## ##STR00271## 9 ##STR00272##
##STR00273## ##STR00274## ##STR00275## 10 ##STR00276## ##STR00277##
##STR00278## ##STR00279## 8-1 ##STR00280## ##STR00281##
##STR00282## ##STR00283## 2 ##STR00284## ##STR00285## ##STR00286##
##STR00287## 3 ##STR00288## ##STR00289## ##STR00290## ##STR00291##
4 ##STR00292## ##STR00293## ##STR00294## ##STR00295## 5
##STR00296## ##STR00297## ##STR00298## ##STR00299## 6 ##STR00300##
##STR00301## ##STR00302## ##STR00303## 7 ##STR00304## ##STR00305##
##STR00306## ##STR00307## 8 ##STR00308## ##STR00309## ##STR00310##
##STR00311## 9 ##STR00312## ##STR00313## ##STR00314## ##STR00315##
10 ##STR00316## ##STR00317## ##STR00318## ##STR00319## 11
##STR00320## ##STR00321## ##STR00322## ##STR00323## 12 ##STR00324##
##STR00325## ##STR00326## ##STR00327## 13 ##STR00328## ##STR00329##
##STR00330## ##STR00331## 9-1 ##STR00332## ##STR00333##
##STR00334## ##STR00335## 2 ##STR00336## ##STR00337## ##STR00338##
##STR00339## 3 ##STR00340## ##STR00341## ##STR00342## ##STR00343##
4 ##STR00344## ##STR00345## ##STR00346## ##STR00347## 5
##STR00348## ##STR00349## ##STR00350## ##STR00351## 6 ##STR00352##
##STR00353## ##STR00354## ##STR00355## 7 ##STR00356## ##STR00357##
##STR00358## ##STR00359## 8 ##STR00360## ##STR00361## ##STR00362##
##STR00363## 9 ##STR00364## ##STR00365## ##STR00366## ##STR00367##
10 ##STR00368## ##STR00369## ##STR00370## ##STR00371## 11
##STR00372## ##STR00373## ##STR00374## ##STR00375## 12 ##STR00376##
##STR00377## ##STR00378## ##STR00379## 13 ##STR00380## ##STR00381##
##STR00382## ##STR00383## 14 ##STR00384## ##STR00385## ##STR00386##
##STR00387## 10-1 ##STR00388## ##STR00389## ##STR00390##
##STR00391## 2 ##STR00392## ##STR00393## ##STR00394## ##STR00395##
3 ##STR00396## ##STR00397## ##STR00398## ##STR00399## 4
##STR00400## ##STR00401## ##STR00402## ##STR00403## 5 ##STR00404##
##STR00405## ##STR00406## ##STR00407## 6 ##STR00408## ##STR00409##
##STR00410## ##STR00411## 7 ##STR00412## ##STR00413## ##STR00414##
##STR00415## 8 ##STR00416## ##STR00417## ##STR00418## ##STR00419##
9 ##STR00420## ##STR00421## ##STR00422## ##STR00423## 11-1
##STR00424## ##STR00425## ##STR00426## ##STR00427## 2 ##STR00428##
##STR00429## ##STR00430## ##STR00431## 3 ##STR00432## ##STR00433##
##STR00434## ##STR00435## 4 ##STR00436## ##STR00437## ##STR00438##
##STR00439## 5 ##STR00440## ##STR00441## ##STR00442## ##STR00443##
6 ##STR00444## ##STR00445## ##STR00446## ##STR00447## 12-1
##STR00448## ##STR00449## ##STR00450## ##STR00451## 2 ##STR00452##
##STR00453## ##STR00454## ##STR00455## 3 ##STR00456## ##STR00457##
##STR00458## ##STR00459## 4 ##STR00460## ##STR00461## ##STR00462##
##STR00463## 5 ##STR00464## ##STR00465## ##STR00466## ##STR00467##
6 ##STR00468## ##STR00469## ##STR00470## ##STR00471## 7
##STR00472## ##STR00473## ##STR00474## ##STR00475## 8 ##STR00476##
##STR00477## ##STR00478## ##STR00479## 9 ##STR00480## ##STR00481##
##STR00482## ##STR00483## 10 ##STR00484## ##STR00485## ##STR00486##
##STR00487## 11 ##STR00488## ##STR00489## ##STR00490## ##STR00491##
13-1 ##STR00492## ##STR00493## ##STR00494## ##STR00495## 2
##STR00496## ##STR00497## ##STR00498## ##STR00499## 3 ##STR00500##
##STR00501## ##STR00502## ##STR00503## 4 ##STR00504## ##STR00505##
##STR00506## ##STR00507## 5 ##STR00508## ##STR00509## ##STR00510##
##STR00511## 6 ##STR00512## ##STR00513## ##STR00514## ##STR00515##
14-1 ##STR00516## ##STR00517## ##STR00518## ##STR00519##
2 ##STR00520## ##STR00521## ##STR00522## ##STR00523## 3
##STR00524## ##STR00525## ##STR00526## ##STR00527## 4 ##STR00528##
##STR00529## ##STR00530## ##STR00531## 5 ##STR00532## ##STR00533##
##STR00534## ##STR00535## 15-1 ##STR00536## ##STR00537##
##STR00538## ##STR00539## 2 ##STR00540## ##STR00541## ##STR00542##
##STR00543## 3 ##STR00544## ##STR00545## ##STR00546## ##STR00547##
4 ##STR00548## ##STR00549## ##STR00550## ##STR00551## 5
##STR00552## ##STR00553## ##STR00554## ##STR00555## 6 ##STR00556##
##STR00557## ##STR00558## ##STR00559## 7 ##STR00560## ##STR00561##
##STR00562## ##STR00563## 8 ##STR00564## ##STR00565## ##STR00566##
##STR00567## 9 ##STR00568## ##STR00569## ##STR00570## ##STR00571##
10 ##STR00572## ##STR00573## ##STR00574## ##STR00575## 16-1
##STR00576## ##STR00577## ##STR00578## ##STR00579## 2 ##STR00580##
##STR00581## ##STR00582## ##STR00583## 3 ##STR00584## ##STR00585##
##STR00586## ##STR00587## 4 ##STR00588## ##STR00589## ##STR00590##
##STR00591## 5 ##STR00592## ##STR00593## ##STR00594## ##STR00595##
6 ##STR00596## ##STR00597## ##STR00598## ##STR00599## 7
##STR00600## ##STR00601## ##STR00602## ##STR00603## 8 ##STR00604##
##STR00605## ##STR00606## ##STR00607## 17-1 ##STR00608##
##STR00609## ##STR00610## ##STR00611## 2 ##STR00612## ##STR00613##
##STR00614## ##STR00615## 3 ##STR00616## ##STR00617## ##STR00618##
##STR00619## 4 ##STR00620## ##STR00621## ##STR00622## ##STR00623##
5 ##STR00624## ##STR00625## ##STR00626## ##STR00627## 6
##STR00628## ##STR00629## ##STR00630## ##STR00631## 7 ##STR00632##
##STR00633## ##STR00634## ##STR00635## 8 ##STR00636## ##STR00637##
##STR00638## ##STR00639##
[0190] Of the above specific examples, (1-1), (1-5), (1-7), (2-1),
(3-1), (4-2), (4-6), (7-2), (7-7), (7-8), (7-9), and (9-7) are
especially preferable.
[0191] The electron injecting layer 133B, for enhancing electron
injecting property by effectively preventing leakage of electric
current between the cathode 14 and the organic layer 13, is formed
of an insulator, semiconductor, or the like.
[0192] Next, a manufacturing method of an OELD 1 will be
described.
[0193] A preparation example of an OELD in which the anode 12, the
hole transporting layer 131A, the emitting layer 132, the electron
injecting layer 133B, and the cathode 14 are sequentially provided
on the light-transmissive substrate 11 will be described.
[0194] First, a film is formed of anode materials at a thickness of
1 .mu.m or less, preferably between 10 nm and 200 nm, by vapor
deposition, sputtering, or the like on an appropriate
light-transmissive substrate 11.
[0195] Next, the hole transporting layer 131A is provided on the
anode 12.
[0196] The hole transporting layer 131A can be formed by vacuum
deposition, spin coating, casting, LB method or the like, but is
preferably formed by coating method.
[0197] It is preferable that the thickness be appropriately
selected in a range from 5 nm to 5 .mu.m.
[0198] Next, the emitting layer 132 is formed by coating
process.
[0199] More specifically, a host material, a first dopant material,
and a second dopant material, each in a predetermined amount, is
dissolved in a solvent to provide an organic EL material containing
solution.
[0200] For this organic-electroluminescent-material-containing
solution, a coating method such as spin coating, casting,
microgravure coating, gravure coating, bar coating, roll coating,
wire bar coating, dip coating, spray coating, screen printing,
flexographic printing, offset printing, or the like may be
employed.
[0201] Screen printing, flexographic printing, offset printing,
inkjet printing, and the like, in which pattern formation and
coloring distinctively in multiple colors, are preferable.
[0202] Examples of solvent include aromatic solvents which may
include an alkoxy group or halogen, such as benzene, toluene,
xylene, ethylbenzene, diethylbenzene, ethylbiphenyl,
isopropylbiphenyl, anisole, chlorobenzene, dichlorobenzene,
chlorotoluene, and the like.
[0203] Halogenated hydrocarbon type solvent such as
dichloromethane, dichloroethane, chloroform, carbon tetrachloride,
tetrachloroethane, or trichloroethane is used as solvent. Ether
type solvent such as dibutyl ether, tetrahydrofuran, or dioxane is
also used as a solvent.
[0204] A viscosity control reagent may be mixed into the
organic-electroluminescent-material-containing solution to control
the viscosity of the organic-electroluminescent-material-containing
solution. The viscosity control reagent includes, for example, an
alcohol type solution, ketone type solution, paraffin type
solution, alkyl-substituted aromatic solution, and the like. It is
preferable that the alcohol type solution or the alkyl-substituted
aromatic solution be employed.
[0205] Examples of the alcohol type solution include methanol,
ethanol, propanol, n-butanol, s-butanol, 2-methyl-1-butanol,
2-methyl-2-butanol, 3-methyl-2-butanol, t-butanol, n-pentanol,
4-methyl-2-pentanol, 3-methyl-1-pentyne-3-ol, n-hexanol,
2-ethylhexanol, 3,5-dimethyl-1-hexyn-3-ol, n-heptanol,
3,3,5-trimethylhexanol, 3-heptanol, n-octanol, 2-octanol,
n-nonanol, n-decanol, methylcyclohexanol, cyclohexanol,
.alpha.-terpineol, neopentyl alcohol, glycidol, methyl cellosolve,
ethyl cellosolve, ethylene glycol, propanediol, butanediol, benzyl
alcohol, and the like. The alcohols mentioned above may be linear
or branched.
[0206] The alkyl-substituted aromatic solution includes linear or
branched butylbenzene, dodecylbenzene, tetralin, cyclohexylbenzene,
dicyclohexylbenzene, 1,1-bis(3,4-dimethylphenyl)ethane,
3-methyldiphenyl ether, and the like.
[0207] The viscosity control reagents may be used alone or in
combination of a plurality thereof.
[0208] Next, the electron injecting layer 133B is provided on the
emitting layer 132.
[0209] The electron injecting layer 133B may be formed by vacuum
deposition, but may also be formed by a coating method.
[0210] Lastly, the cathode 14 is layered to obtain the OELD 1.
[0211] The cathode 14 is formed of metal by vapor deposition,
sputtering, or the like.
[0212] It should be noted that vacuum deposition is preferable to
prevent the organic layer 13 (base layer) from being damaged during
the film-formation.
[0213] The thickness of each organic layer of the OELD 1 is not
particularly limited. However, since too small a thickness is
likely to cause defects such as a pin hole whereas too large a
thickness requires high voltage to be applied and decreases
efficiency, generally a thickness within a range from several nm to
1 .mu.m is preferable.
[0214] Incidentally, in the case of applying direct voltage to the
OELD 1, by arranging the anode 12 to have positive polarity and the
cathode 14 to have negative polarity and applying voltage from 5 to
40 V, light emission can be observed. When the voltage is applied
to an inversely-polarized arrangement, the current does not pass
through, so that light emission does not take place. In the case of
applying alternating current, uniform light emission is observed
only if the anode 12 has the positive polarity and the cathode 14
has the negative polarity. Alternating current of any waveform may
be applied.
EXAMPLES
[0215] Examples of the present invention will be described in
detail below, but the present invention is not limited to the
examples.
[0216] Note that the properties of compounds used in the examples
and devices prepared were evaluated in the following manner.
(1) Energy gap: energy gap was measured from an absorption end of
absorption spectrum of benzene. To be specific, the absorption
spectrum is measured with a commercially available
ultraviolet-visible spectrophotometer, and the energy gap is
calculated from a wavelength at which the absorption spectrum
appears. (2) Luminance: luminance was measured by a
spectroradiometer (CS-1000 manufactured formerly by Minolta Co.,
Ltd, now by Konica Minolta Sensing, Inc.). (3) Luminous intensity
of maximum wavelength of light emission: a single layer film of an
emitting layer (a first emitting layer) only including the first
dopant as a dopant and a single layer film of an emitting layer (a
second emitting layer) only including the second dopant as a dopant
were prepared under the same condition as an electroluminescence
device (hereafter abbreviated to EL device) to be prepared. A
fluorescence spectrum of each of the single layer films was
measured by a commercially available fluorescence meter. A
fluorescent intensity I.sub.a of the first emitting layer at the
luminescent maximum wavelength a of the first emitting layer was
measured from the acquired fluorescence spectrum of the first
emitting layer. Similarly, a fluorescent intensity I.sub.b of the
second emitting layer at the luminescent maximum wavelength b of
the second emitting layer from the obtained fluorescence spectrum
of the second emitting layer was prepared.
[0217] If the luminescent maximum wavelengths of the first and
second emitting layers are sufficiently apart from each other,
luminous intensities I.sub.a and I.sub.b at wavelengths of a and b
of the luminescence spectrum of the EL device can respectively
approximate I.sub.1 and I.sub.2.
[0218] If the luminescent maximum wavelengths of the first emitting
layer and the second emitting layer are close to each other, the
luminescence spectrum of the EL device can be assumed to be a sum
of the luminescence spectrum from the first emitting layer and the
luminescence spectrum from the second emitting layer.
[0219] Accordingly, in the obtained fluorescence spectrum of the
first emitting layer, fluorescent intensities I.sub.1a and I.sub.1b
of the wavelengths a and b were observed. Similarly, in the
fluorescence spectrum of the second emitting layer, fluorescent
intensities I.sub.2a and I.sub.2b of the wavelengths a, b were
observed. The following formulae stand for I.sub.1 and I.sub.2.
I.sub.a=I.sub.1*I.sub.1a+I.sub.2*I.sub.2a
I.sub.b=I.sub.1*I.sub.1b+I.sub.2*I.sub.2b
[0220] A ratio of I.sub.1 and I.sub.2 was obtained from the above
formulae.
(4) Luminous efficiency: a luminous efficiency was calculated from
a current density measured by a multimeter and luminance (100 nit).
(5) CIE color coordinate: CIE color coordinates were measured and
obtained in the same manner as (2). (6) Half life: a device sealed
under conditions of initial luminance of 1000 nit and a constant
current was measured at room temperature. (7) Electron mobility:
The electron mobility was calculated by a Time of flight method. In
specific, an object having a configuration of ITO/organic layer
(electron injecting layer and the like, thickness of layer 1 to 2
.mu.m)/Al was measured for a time characteristic of transient
current generated by light irradiation (transient characteristic
time), and the electron mobility was calculated by the following
formulae.
electron mobility=(thickness of organic layer).sup.2/(transient
characteristic time-electric intensity)
[0221] Compounds used in the examples will be shown below.
##STR00640## ##STR00641##
[0222] Data of energy gap, affinity level, and electron mobility of
the above compounds were as follows.
[0223] For D1, Eg=2.9 eV, Af=2.5 eV
[0224] For H1, Eg=3.0 eV, Af=2.7 eV
[0225] For D2, Eg=2.8 eV, Af=2.8 eV
For D3, Eg=2.6 eV, Af=3.0 eV
[0226] Electron mobility of ET-1 is 4*10.sup.-4 cm.sup.2/Vs
(provided being in an electric field of E=5*10.sup.5 V/cm)
[0227] Electron mobility of Alq is 5*10.sup.-6 cm.sup.2/Vs
(provided being in an electric field of E=5*10.sup.5 V/cm).
Comparative Example 1
[0228] A glass substrate of 25 mm*75 mm*1.1 mm (thickness) having
an ITO transparent electrode (manufactured by Geomatec Co., Ltd)
went through 5 minutes of ultrasonic cleaning in isopropyl alcohol
and then 30 minutes of UV ozone cleaning.
[0229] On the glass substrate with a transparent electrode that has
been cleaned, a mixture of polyethylene-dioxy-thiophene/polystyrene
sulphonic acid (PEDOT.PSS) used for a hole injecting layer was
formed into a 50 nm thick film by spin coating.
[0230] Next, a toluene solution (0.6% by mass) of the above polymer
1 (Mw: 145000) was formed into a 20 nm thick film before it was
dried at 170.degree. C. for 30 minutes.
[0231] After that, the film-formed substrate was transferred to a
vacuum deposition device.
[0232] An emitting layer was constituted by two layers. 20 nm of
the dopant D1 and the host H1 (at a doping concentration of 5% by
mass) made the first emitting layer, and 20 nm of the dopant D2/the
host H1 (5% by mass) made the second emitting layer, which were
sequentially formed by vapor deposition.
[0233] A 20 nm thick tris(8-quinolinol)aluminum film (hereafter
abbreviated to "Alq film") was formed on this film.
[0234] This Alq film functioned as an electron transporting
layer.
[0235] Lithium fluoride was formed into a film of 1 nm as an
electron injecting layer on this.
[0236] Lastly, aluminum was formed into a film of 150 nm to
constitute a cathode.
[0237] When current was delivered to evaluate the performance,
luminance 6.7 cd/A, chromaticity (0.15, 0.17), half life LT50=3000
h at 1000 cd/m.sup.2, drive voltage=6.5 V at 10 mA/cm.sup.2, ratio
of luminous intensities I.sub.1/I.sub.2=80/20 were obtained.
Comparative Example 2
[0238] A device was prepared in the same manner as the comparative
example 1 except that the emitting layer was a 40 nm thick single
layer and that 5% by mass of the dopant D1 and 1% by mass of the
dopant D2 were doped to the host H1.
[0239] As a result, luminance 10 cd/A, chromaticity (0.15, 0.30),
half life LT 50=5000 h at 1000 cd/m.sup.2, drive voltage=6.5 V at
10 mA/cm.sup.2, ratio of luminous intensities I.sub.1/I.sub.2=0/100
were obtained.
[0240] That is to say, though the doping concentration was low,
light emission by the second dopant D2 was now the only light
emission, which was in blue green.
Comparative Example 3
[0241] In the comparative example 1, the concentration of the
second dopant D2 of the second emitting layer was changed to 1% by
mass.
[0242] A device was prepared otherwise in the same manner as the
comparative example 1.
[0243] As a result, 7.0 cd/A, chromaticity (0.15, 0.16), half life
LT50=3000 h at 1000 cd/m.sup.2, voltage 6.5 V at 10 mA/cm.sup.2,
ratio of luminous intensities I.sub.1/I.sub.2=90/10 were
obtained.
[0244] Color purity improved as the light emission of the second
dopant decreased, but effect was insufficient in terms of lifetime
extension.
Comparative Example 4
[0245] In the comparative example 1, the first emitting layer was
now the only emitting layer, whose thickness was changed to 40 nm,
and ET-1 was formed as an electron transporting layer by vapor
deposition. A device was prepared otherwise in the same manner as
the comparative example 1.
[0246] As a result, luminance 8 cd/A, chromaticity (0.15, 0.15),
half life LT50=300 h, drive voltage=3.5 V at 10 mA/cm.sup.2, a
ratio of luminous intensities I.sub.1/I.sub.2=100/0 were
obtained.
[0247] Since ET-1 was employed for an electron transporting layer,
the drive voltage decreased, but the lifetime was shorter than the
comparative example 1.
Example 1
[0248] In the comparative example 4, the emitting layer was formed
in a coating method.
[0249] That is, cyclohexanone was used as a solvent, to which 5% by
mass of the dopant D1 and 0.5% by mass of the dopant D2 were doped
to prepare a solution, from which an emitting layer constituted of
a single layer was formed by spin coating. The emitting layer was
20 nm thick.
[0250] A device was prepared otherwise in the same manner as the
comparative example 4.
[0251] As a result, luminance of 8 cd/A, chromaticity (0.15, 0.16),
half life LT 50=4000 h at 1000 cd/m.sup.2, drive voltage=3.5 V at
10 mA/cm.sup.2, ratio of luminous intensities I.sub.1/I.sub.2=95/5
were obtained.
[0252] By thinly doping the second dopant D2 to the emitting layer
of a single layer, light emission was reduced to one from the first
dopant D1, the lifetime was longer than the comparative example 1,
and the drive voltage decreased by 3V on account of absence of the
second emitting layer unlike the comparative example 1.
Example 2
[0253] A device was prepared in the same manner as the example 1
except that the same electron transporting layer was formed as the
comparative example 1.
[0254] As a result, luminance 7 cd/A, chromaticity (0.15, 0.16),
half life LT 50=5000 h at 1000 cd/m.sup.2, drive voltage=6.5 V at
10 mA/cm.sup.2, ratio of luminous intensities I.sub.1/I.sub.2=95/5
were obtained.
[0255] The voltage rose compared to the example 1, but the lifetime
extended further, and fine chromaticity was observed.
Example 3
[0256] A device was prepared in the same manner as the example 1
except that a concentration of the second dopant D2 was 0.01% by
mass.
[0257] As a result, luminance 8 cd/A, chromaticity (0.15, 0.15),
half life LT50=3800 h at 1000 cd/m.sup.2, drive voltage=3.5 V at 10
mA/cm.sup.2, ratio of luminous intensities I.sub.1/I.sub.2=99/1
were obtained.
Example 4
[0258] The same preparation as in the example 1, was conducted
except that the D2 was doped in 0.4% by mass.
[0259] Hereinafter, see a table 1 below for the results.
Example 5
[0260] A device was prepared in the same manner as the example 1
except that a concentration of the second dopant D2 was 0.05% by
mass.
Example 6
[0261] A device was prepared in the same manner as the example 1
except that a concentration of the second dopant D2 was 0.03% by
mass.
Example 7
[0262] The same preparation as in the example 1 was conducted
except that the D2 was changed to D3, which was doped in 0.05% by
mass.
Example 8
[0263] The same preparation as in the example 1 was conducted
except that the D2 was changed to D3, which was doped in 0.3% by
mass.
TABLE-US-00002 TABLE 1 Doping Current Ratio of Concentration
Efficiency Half Life Luminous (mass %) L/J Chromaticity LT50*.sup.2
Voltage*.sup.2 Intensities D1 D2 D3 (cd/A) x y (hr) (V)
I.sub.1/I.sub.2 Comparative 5.0 5.0 -- 6.7 0.15 0.17 3000 6.5 80/20
Example 1 Comparative 5.0 1.0 -- 10.0 0.15 0.3 5000 6.5 0/100
Example 2 Comparative 5.0 1.0 -- 7.0 0.15 0.3 3000 6.5 0/100
Example 3 Comparative 5.0 -- -- 8.0 0.15 0.15 300 3.5 100/0 Example
4 Example 1 5.0 0.5 -- 8.0 0.15 0.16 4000 3.5 95/5 Example 2 5.0
0.5 -- 7.0 0.15 0.16 5000 6.5 95/5 Example 3 5.0 0.01 -- 8.0 0.15
0.15 3800 3.5 99/1 Example 4 5.0 0.4 -- 8.0 0.15 0.16 3800 3.5 96/4
Example 5 5.0 0.05 -- 8.0 0.15 0.15 3500 3.5 98/2 Example 6 5.0 0.3
-- 8.0 0.15 0.15 3800 3.5 97/3 Example 7 5.0 -- 0.05 8.0 0.15 0.16
5000 3.5 98/2 Example 8 5.0 -- 0.3 8.5 0.16 0.16 5000 3.5 97/3
*.sup.1In the case of 1000 cd/m.sup.2 *.sup.2In the case of 10
mA/cm.sup.2
[0264] If the examples 1 to 8 are compared to the comparative
example 4, whereas the emitting layer is a single layer and the
primarily-emitting first dopant is the only dopant contained in the
comparative example 4, a single emitting layer contains not only
the primarily-emitting first dopant but also a small amount of the
second dopant in the examples 1 to 8.
[0265] In all of the comparative example 4 and the examples 1 to 8,
the chromaticity is substantially the same, properly being blue,
but the lifetime is enormously longer in the examples 1 to 8.
[0266] Accordingly, it has been shown that by containing a first
dopant and a small amount of a second dopant in one emitting layer
as is the case in the present invention, a device possessing a very
long lifetime and at the same time a fine color purity can be
prepared.
[0267] Further, from the comparison between the comparative example
1 and the examples 1 to 8, similar effects can be expected in a
case like comparative example 1 where an emitting layer includes
two layers, one of which is a first emitting layer containing a
first dopant and the other is a second emitting layer containing a
second dopant, but it has been shown that the arrangement of the
present invention can extraordinarily improve the color purity and
the lifetime.
[0268] Furthermore, though color purity is somewhat improved if the
emitting layer includes the two layers and the concentration of the
second dopant D2 in the second emitting layer is reduced as have
been done in the comparative example 3 to rectify the
disadvantageous color purity of the comparative example 1, since
the emitting layer is divided into two, lifetime-extending effects
on par with the examples of the present invention are not
provided.
[0269] Incidentally, it would only prove impossible to provide a
lower concentration of the second dopant in the second emitting
layer than the comparative example 3 by vapor deposition, which
makes it necessary to, similarly to the examples, employ a coating
method to lower the dopant concentration.
[0270] It should be noted that the present invention is not limited
to the above embodiments and the examples, but is permissive of
modification without diverting from the inventive concept of the
present invention.
[0271] A content ratio of the second dopant is not limited to the
above examples, where the second dopant may be contained in any
amount as far as the ratio of the luminous intensities of the first
dopant and the second dopant is twelve times or larger.
[0272] An energy gap of the second dopant may preferably be smaller
than an energy gap of the first dopant, but an energy gap of the
second dopant may be larger than an energy gap of the first dopant
as well. In this case, a function as an electron trap is still
provided if an Af of the second dopant is larger by 0.2 eV or more
than an Af of the host.
[0273] An electron transporting layer is not limited to the above
compounds, but as a matter of course can also be a known electron
transporting material, which still provides the effects of the
present invention.
[0274] Configurations of a device, materials of layers, and the
like will be listed below as variations of the present invention,
but as a matter of course the present invention is not limited to
those listed.
(1) Configurations of OELD
[0275] Device configurations of an OELD will be described
hereinafter.
[0276] Typical device configurations of an OELD include the
following structures (a) to (m) and the like.
(a) anode/emitting layer/cathode (b) anode/hole injecting
layer/emitting layer/cathode (c) anode/emitting layer/electron
injecting layer/cathode (d) anode/hole injecting layer/emitting
layer/electron injecting layer/cathode (e) anode/organic
semiconductor layer/emitting layer/cathode (f) anode/organic
semiconductor layer/electron blocking layer/emitting layer/cathode
(g) anode/organic semiconductor layer/emitting layer/adhesion
improving layer/cathode (h) anode/hole injecting layer/hole
transporting layer/emitting layer/electron injecting layer/cathode
(i) anode/insulating layer/emitting layer/insulating layer/cathode
(j) anode/inorganic semiconductor layer/insulating layer/emitting
layer/insulating layer/cathode (k) anode/organic semiconductor
layer/insulating layer/emitting layer/insulating layer/cathode (l)
anode/insulating layer/hole injecting layer/hole transporting
layer/emitting layer/insulating layer/cathode (m) anode/insulating
layer/hole injecting layer/hole transporting layer/emitting
layer/electron injecting layer/cathode
(2) Light-Transmissive Substrate
[0277] An OELD is prepared on a light-transmissive substrate. Here,
a light-transmissive substrate, which is a substrate for supporting
OELDs, preferably is a smooth substrate whose transmittance of
visible light from 400 nm to 700 nm is 50% or more
[0278] Specifically, a glass plate, a polymer plate, and the like
are preferable.
[0279] To be more specific, the glass plate includes soda-lime
glass, barium/strontium-containing glass, lead glass,
aluminosilicate glass, borosilicate glass, barium borosilicate
glass, quartz, and the like.
[0280] The polymer plate includes polycarbonate, acryl,
polyethylene terephthalate, polyether sulfide, polysulfone and the
like.
(3) Anode
[0281] A task of an anode of an OELD is to inject a hole to a hole
transporting layer or an emitting layer, so that possession of a
work function of 4.5 eV or greater is effective. Examples of anode
materials include indium-tin oxide (ITO), tin oxide (NESA), indium
zinc oxide (IZO), gold, silver, platinum, copper, and the like.
[0282] An anode can be prepared by forming a thin film out of these
electrode materials by vapor deposition, sputtering, or the
like.
[0283] When light emission from an emitting layer is acquired from
an anode, it is preferable that the anode possess 10% or more of
transmittance for light emission. It is also preferable that sheet
resistance of the anode be equal to or less than several hundred
.OMEGA./.quadrature.. Though dependent on material, a thickness of
an anode is preferably selected normally within a range from 10 nm
to 1 .mu.m and preferably within a range from 10 to 200 nm.
(4) Hole Injecting and Transporting Layer
[0284] Hole injecting and transporting layers, which help injecting
holes to an emitting layer and transport holes to an emitting
region, has a high hole mobility and normally has a small
ionization energy of 5.5 eV or less. It is preferable that such
hole injecting and transporting layers be materials which transport
holes to an emitting layer at a lower electric intensity, and
further preferable that a hole mobility be, for example, at least
10.sup.-4 cm.sup.2/Vsec when applied an electrical field of
10.sup.4 to 10.sup.6 V/cm.
[0285] Materials that form hole injecting and transporting layers
are not particularly limited as far as the above preferable
characteristics are exhibited, and may appropriately be selected
from materials that have conventionally been used as materials for
transporting electric charges of holes in photoconducting materials
or known materials used for a hole injecting layer of an OELD.
[0286] Examples include a triazole derivative (See, U.S. Pat. No.
3,112,197 etc.), oxadiazole derivative (See, U.S. Pat. No.
3,189,447 etc.), imidazole derivative (See, JP-B-37-16096 etc.),
polyarylalkane derivative (See, U.S. Pat. No. 3,615,402, U.S. Pat.
No. 3,820,989, U.S. Pat. No. 3,542,544, JP-B-45-555, JP-B-51-10983,
JP-A-51-93224, JP-A-55-17105, JP-A-56-4148, JP-A-55-108667,
JP-A-55-156953, JP-A-56-36656, etc.), pyrazoline derivative and
pyrazolone derivative (See, U.S. Pat. No. 3,180,729, U.S. Pat. No.
4,278,746, JP-A-55-88064, JP-A-55-88065, JP-A-49-105537,
JP-A-55-51086, JP-A-56-80051, JP-A-56-88141, JP-A-57-45545,
JP-A-54-112637, JP-A-55-74546, etc.), phenylenediamine derivative
(See, U.S. Pat. No. 3,615,404, JP-B-51-10105, JP-B-46-3712,
JP-B-47-25336, JP-A-54-53435, JP-A-54-110536, JP-A-54-119925,
etc.), arylamine derivative (See, U.S. Pat. No. 3,567,450, U.S.
Pat. No. 3,180,703, U.S. Pat. No. 3,240,597, U.S. Pat. No.
3,658,520, U.S. Pat. No. 4,232,103, U.S. Pat. No. 4,175,961, U.S.
Pat. No. 4,012,376, JP-B-49-35702, JP-B-39-27577, JP-A-55-144250,
JP-A-56-119132, JP-A-56-22437, F.R.G. Patent No. 1,110,518 etc.),
amino-substituted chalcone derivative (See, U.S. Pat. No. 3,526,501
etc.), oxazole derivative (that disclosed in U.S. Pat. No.
3,257,203 etc.), styrylanthracene derivative (See, JP-A-56-46234
etc.), fluorenone derivative (See, JP-A-54-110837 etc.), hydrazone
derivative (See, U.S. Pat. No. 3,717,462, JP-A-54-59143,
JP-A-55-52063, JP-A-55-52064, JP-A-55-46760, JP-A-55-85495,
JP-A-57-11350, JP-A-57-148749, JP-A-02-311591, etc.), stilbene
derivative (See, JP-A-61-210363, JP-A-61-228451, JP-A-61-14642,
JP-A-61-72255, JP-A-62-47646, JP-A-62-36674, JP-A-62-10652,
JP-A-62-30255, JP-A-60-93455, JP-A-60-94462, JP-A-60-174749,
JP-A-60-175052, etc.), silazane derivative (U.S. Pat. No.
4,950,950), polysilane type (JP-A-02-204996), aniline-type
copolymer (JP-A-02-282263), conductive high-molecular oligomer
disclosed in JP-A-1-211399 (particularly thiophene oligomer), and
the like.
[0287] In addition, thiophene polymer such as
poly(alkylthiophene)polymer may be employed. Polydioxythiophene,
and further, poly(3,4-dioxythiophene) may preferably be employed,
for example. Aniline type may be polymer (polyaniline), too.
[0288] Besides, the following formula may also be included.
Q.sup.1-G-Q.sup.2
(In the formula, Q.sup.1 and Q.sup.2 are portions having at least
one tertiary amine and G is a linking group.)
[0289] Still further preferably, an amine derivative represented by
the following formula (17) may be employed.
##STR00642##
[0290] In the above formula (17), Ar.sup.21 to Ar.sup.24 are a
substituted or unsubstituted aromatic ring having 6 to 50 ring
carbon atoms or substituted or unsubstituted heteroaromatic ring
having 5 to 50 ring atoms.
[0291] R.sup.21 and R.sup.22 are substituent groups, and the signs
s and t are each an integer from 0 to 4.
[0292] Ar.sup.21 and Ar.sup.22 may be connected to each other to
form a ring structure, and Ar.sup.23 and Ar.sup.24 may be connected
to each other to form a ring structure.
[0293] R.sup.21 and R.sup.22 may also be connected to each other to
form a ring structure.
[0294] Substituent groups of Ar.sup.21 to Ar.sup.24 and R.sup.21
and R.sup.22 are a substituted or unsubstituted aromatic ring
having 6 to 50 ring carbon atoms, substituted or unsubstituted
heteroaromatic ring having 5 to 50 ring atoms, alkyl group having 1
to 50 carbons, alkoxy group having 1 to 50 carbons, alkylaryl group
having 1 to 50 carbons, aralkyl group having 1 to 50 carbons,
styryl group, amino group substituted by an aromatic ring having 6
to 50 ring carbon atoms or by a heteroaromatic ring having 5 to 50
ring atoms, or aromatic ring having 6 to 50 ring carbon atoms or
heteroaromatic ring having 5 to 50 ring atoms substituted by an
amino group substituted by an aromatic ring having 6 to 50 ring
carbon atoms or by a heteroaromatic ring having 5 to 50 ring
atoms.
[0295] The above materials can be employed as materials for the
hole injecting layer, but it is preferable that porphyrin compounds
(those disclosed in JP-A-63-2956965 etc.) and aromatic tertiary
amine compounds and styrylamine compounds (See, U.S. Pat. No.
4,127,412, JP-A-53-27033, JP-A-54-58445, JP-A-54-149634,
JP-A-54-64299, JP-A-55-79450, JP-A-55-144250, JP-A-56-119132,
JP-A-61-295558, JP-A-61-98353, JP-A-63-295695, etc.) be employed
and further preferable that aromatic tertiary amine compounds be
employed.
[0296] Another example is a compound disclosed in U.S. Pat. No.
5,061,569, which contains two condensed aromatic rings within the
molecules, such as 4,4'-bis(N-(1-naphthyl)-N-phenylamino)biphenyl
(hereafter abbreviated to NPD) or the like. Still another example
is 4,4',4''-tris(N-(3-methylphenyl)-N-phenylamino)triphenylamine
(hereafter abbreviated to MTDATA) disclosed in JP-A-04-308688, in
which three triphenylamine units are connected in starburst
fashion, or the like.
[0297] Inorganic compounds such as p-type Si, p-type SiC, and the
like, as well as aromatic dimethylidine compounds mentioned above
as materials for the emitting layer, may also be employed as
materials for hole injecting layers.
[0298] Besides, it is preferable that at least one layer of an
emitting layer and an organic layer between the emitting layer and
an anode contain an oxidizing agent, which preferably includes an
electron withdrawing compound or an electron acceptor,
specifically, a Lewis acid, various quinone derivatives,
dicyanoquinodimethane derivative, and salts formed by aromatic
amine and Lewis acid and the like, the Lewis acid including iron
chloride, antimony chloride, aluminum chloride, and the like.
[0299] In addition, a nitrogen-containing heterocycle derivative
which is represented by the following formula (18) and is disclosed
in Japanese Patent No. 3571977 may also be employed.
##STR00643##
[0300] In the above formula (18), R.sub.1 to R.sub.6 represent one
of a substituted or unsubstituted alkyl group, substituted or
unsubstituted aryl group, substituted or unsubstituted aralkyl
group, and substituted or unsubstituted heterocyclic group. Here,
R.sub.1 to R.sub.6 may be identical to or different from each
other. R.sub.1 and R.sub.2 may form a condensed ring, R.sub.3 and
R.sub.4 may form a condensed ring, and so may R.sub.5 and R.sub.6;
or R.sub.1 and R.sub.6 may form a ring, R.sub.2 and R.sub.3 may
form a ring, and so may R.sub.4 and R.sub.5.
[0301] Moreover, compounds represented by the following formula
(19) disclosed in US2004/113547 A1 may also be employed.
##STR00644##
[0302] In the above formula (19), R1 to R6 are a substituent group,
preferably an electron withdrawing group such as a cyano group,
nitro group, sulfonyl group, carbonyl group, trifluoromethyl group,
halogen, and the like.
[0303] The hole injecting and transporting layers can be formed by
film-forming of the above compounds by, for example, vacuum
deposition, spin coating, casting, LB method, or the like.
Thickness of the hole injecting and transporting layers are not
particularly limited, but normally are 5 nm to 5 .mu.m. As far as
the hole injecting and transporting layers contain the compounds
according to the present invention in the hole transporting zone
thereof, the hole injecting and transporting layers may be formed
by a singular layer made of one kind or two or more kinds of the
above compounds, or may be formed by layers of the hole injecting
and transporting layers made of compounds different from the
aforementioned hole injecting and transporting layers. The organic
semiconductor layer, which is a layer that helps hole injection or
electron injection into an emitting layer, appropriately possesses
conductivity of 10.sup.-10 S/cm or more. For materials of the
organic semiconductor layer, conductive oligomer such as
thiophene-containing oligomer, arylamine-containing oligomer
disclosed in JP-A-08-193191, etc. conductive dendrimer such
arylamine-containing dendrimer etc., and the like may be
utilized.
(5) Electron Injecting Layer
[0304] Preferred embodiments of an OELD include a device which
contains a reductive dopant in an electron transporting region or
an interface region between a cathode and an organic layer. Here, a
reductive dopant is defined as a material that can reduce an
electron transporting compound. Accordingly, various materials are
utilized as far as the material possesses proper reductive
property. For example, at least one material selected from a group
of alkali metal, alkali earth metal, rare earth metal, oxide of
alkali metal, halogenide of alkali metal, oxide of alkali earth
metal, halogenide of alkali earth metal, oxide of rare earth metal,
halogenide of rare earth metal, organic complexes of alkali metal,
organic complexes of alkali earth metal, and organic complexes of
rare earth metal may suitably be utilized.
[0305] More specifically, it is preferable that a reductive dopant
possess a work function of 2.9 eV or lower and be at least one
alkali metal selected from a group of Li (work function: 2.9 eV),
Na (work function: 2.36 eV), K (work function: 2.28 eV), Rb (work
function: 2.16 eV), and Cs (work function: 1.95 eV) or at least one
alkali earth metal selected from a group of Ca (work function: 2.9
eV), Sr (work function: 2.0 to 2.5 eV), and Ba (work function: 2.52
eV). More preferred of these reductive dopants is at least one
alkali metal selected from a group of K, Rb, and Cs, a still more
preferred is Rb or Cs, and the most preferred one is Cs. These
alkali metals possess especially high reducing property, so that
doping to an electron injecting region in a relatively small amount
can improve luminance of and extend a lifetime of an OELD. In
addition, as a reductive dopant with a work function of 2.9 eV or
less, combinations of two or more kinds of alkali metal is also
preferable, and a combination which contains Cs such as a
combination of Cs and Na, combination of Cs and K, combination of
Cs and Rb, or combination of Cs, Na, and K are especially
preferable. Since Cs is included in the combinations of the
contained materials, reduction is now efficiently achieved, which
allows doping to an electron injecting region to improve luminance
of and extend lifetime of OELD.
[0306] Further, an electron injecting layer formed by an insulator
or a semiconductor may be provided between the cathode and the
organic layer. At this time, leakage of current is effectively
prevented to improve electron injecting property. For such an
insulator, at least one metal compound selected from a group of
alkali metal chalcogenide, alkaline earth metal chalcogenide,
halogenide of alkali metal, and halogenide of alkali earth metal
may preferably be utilized. A configuration in which the electron
injecting layer is formed by these alkaline metal chalcogenide and
the like is advantageous in that the electron injecting property is
further improved. Specifically, preferred alkali metal chalcogenide
includes, for example, Li.sub.2O, K.sub.2O, Na.sub.2Se and
Na.sub.2O, and preferred alkaline earth metal chalcogenide
includes, for example, CaO, BaO, SrO, BeO, BaS, and CaSe. Preferred
halogenide of alkali metal includes, for example, LiF, NaF, KF,
LiCl, KCl, and NaCl and the like. Preferred halogenide of alkali
earth metal includes, for example, fluorides such as CaF.sub.2,
BaF.sub.2, SrF.sub.2, MgF.sub.2 and BeF.sub.2 and halogenides other
than fluorides.
[0307] A semiconductor that forms the electron transporting layer
includes an oxide, nitride, oxidized nitride, or the like alone or
in combination of two or more kinds, which contains at least one
element of Ba, Ca, Sr, Yb, Al, Ga, In, Li, Na, Cd, Mg, Si, Ta, Sb,
and Zn. Inorganic compounds forming the electron transporting layer
may preferably be microcrystalline or amorphous insulative film. If
an electron transporting layer is formed by these insulative films,
a film with greater uniformity is formed, so that pixel defects
such as dark spots can be reduced. Incidentally, such inorganic
compounds include the aforementioned alkali metal chalcogenide,
alkaline earth metal chalcogenide, halogenide of alkali metal,
halogenide of alkali earth metal, and the like.
(6) Cathode
[0308] An electrode material of a cathode is metal, alloy, an
electrically conductive compound, and a mixture of these, which
possesses a low work function (4 eV or lower) to inject electrons
to electron injecting or transporting layers or emitting layers.
Specific examples of such electrode materials include sodium,
sodium-potassium alloy, magnesium, lithium, magnesium-silver alloy,
aluminum/aluminum oxide, aluminum-lithium alloy, indium, rare earth
metal, and the like.
[0309] These electrode materials are formed into a film by methods
such as vapor deposition, sputtering, and the like to prepare the
cathode.
[0310] Here, when light emission from the emitting layer is
acquired from the cathode (in the case of top emission),
transmittance as to light emission of the cathode preferably is
larger than 10%.
[0311] Sheet resistance of the cathode is preferably several
.OMEGA./.quadrature. or lower, and thickness thereof is normally 10
nm to 1 .mu.m, preferably 50 to 200 nm.
(7) Insulating Layer
[0312] As for an OELD, since an electric field is applied to super
thin film, leakage or short circuit is likely to cause a pixel
defect. To prevent this, an insulative film layer preferably is
inserted between a pair of electrodes.
[0313] Materials used for the insulating layer include, for
example, aluminum oxide, lithium fluoride, lithium oxide, cesium
fluoride, cesium oxide, magnesium oxide, magnesium fluoride,
calcium oxide, calcium fluoride, aluminum nitride, titanium oxide,
silicon oxide, germanium oxide, silicon nitride, boron nitride,
molybdenum oxide, ruthenium oxide, vanadium oxide, and the
like.
[0314] A mixture or layers of these may be employed, too.
[0315] The priority application Number JP2007-112154 upon which
this patent application is based is hereby incorporated by
reference.
* * * * *